A shadowy terror group smuggles a crude nuclear bomb into the United States, then detonates it right in the heart of Washington D.C., setting off a 15 kiloton explosion.

Eighty thousand Americans are killed instantly, including the president, vice president and most of the members of Congress, and more than a hundred thousand more are seriously wounded.

News outlets are soon broadcasting a message they’ve all received from a group claiming responsibility.

It says there are five more bombs hidden in five different cities across the America, and one bomb will be set off each week for the next five weeks unless all American troops based overseas are ordered to immediately return to the U.S. homeland.

The nation is thrown into chaos, as millions scramble to flee the cities, clogging roads and choking telecommunications systems.

The stock market crashes, before trading is halted altogether.

Martial law is declared, amid widespread looting and violence.

That was just one of the nightmare scenarios for a potential nuclear disaster that former U.S. Secretary of Defense William J. Perry vividly described as he delivered the Center for International Security and Cooperation’s annual Drell Lecture on Wednesday.

“My bottom line is that the likelihood of a nuclear catastrophe today is greater than it was during the Cold War,” Perry said.

Most people were “blissfully unaware” of the danger that simmering conflicts in geopolitical flash points around the globe – including Russia, China, North Korea, Iran and Pakistan – could easily turn nuclear, Perry told the Stanford audience.

A new nuclear arms race with Russia

Perry said he had tried to foster closer cooperation between the U.S. and Russia when he headed the Pentagon during the mid ‘90s and helped oversee the joint dismantling of four thousand nuclear weapons.

“When I left the Pentagon, I believed we were well on the way to ending forever that Cold War enmity, but that was not to be,” he said.

William J. Perry shares a video depicting the threat of nuclear terrorism with a Stanford audience.

Since then, relations between the West and Russia have soured badly, prompting Russia to modernize its nuclear arsenal and assume a more aggressive nuclear posture.

“They’re well advanced in rebuilding their Cold War nuclear arsenal, and it is Putin’s stated first priority,” Perry said.

“And they have dropped their former policy of no first use of nuclear weapons, and replaced it with a policy that says nuclear weapons will be their weapon of choice if they are threatened.”

While Perry said he believed Russian president Vladimir Putin did not want to engage in a military conflict with NATO forces, he said he was concerned about the possibility of Russia making a strategic miscalculation and stumbling into a conflict where they might resort to the use of tactical nuclear weapons.

“If they did that there’s no way of predicting or controlling the escalation that would follow thereafter,” Perry said.

Chinese economic problems increasing tensions

In Asia, a slowing Chinese economy could exacerbate domestic political tensions over issues such as wealth inequality and pollution, and encourage Chinese leaders to divert attention from problems at home by focusing on enemies abroad.

“China has had more than 10 percent growth now for almost three decades, but I think there’s trouble ahead,” Perry said.

“The time-proven safety valve for any government that’s in trouble is ultra-nationalism, which in the case of China translates into anti-Americanism and anti-Japanese.”

China has seen a major growth in military expenditures over the last decade, and it has used that investment to build a blue water navy and develop effective anti-ship missiles designed to drive the U.S. Navy hundreds of miles back from the Chinese coastline.

One potential flash point for a conflict between China and the U.S. are the artificial islands that China has been building in the disputed waters of the South China Sea.

“In a sense, China is regarding the South China Sea as a domestic lake, and we regard it and most other countries regard it as international waters, so their actions have been challenged by the U.S. Navy and will continue to be challenged,” Perry said.

North Korea’s growing nuclear threat

Meanwhile, China’s neighbor North Korea has continued to defy the international community and conducted another nuclear test in January.

“North Korea is today building a nuclear arsenal, and I would say clearly it’s of the highest priority in their government, and they have adopted outrageous rhetoric about how they might use those nuclear weapons,” Perry said.

William J. Perry delivers the Drell Lecture in an address entitled "A National Security Walk Around the World."

“These missiles today have only conventional warheads that are of no significant concern, but they are developing nuclear warheads,” Perry said.

“They already have developed a nuclear bomb, and the latest test, as well as tests to come, will be designed to perfect a bomb small enough and compact enough and durable enough to fit into a warhead. If they succeed in doing that, then the bluster will become a real threat.”

Perry said he hoped China and the United States could combine forces and adopt a “carrot and stick” diplomatic approach to force North Korea to abandon its nuclear weapons program – with the United States offering aid and international recognition, and China threatening to cut off supplies of food and aid.

He said he expected to see “more acting out” from the North Korean regime in the coming months, in the form of further nuclear and rocket tests.

Like it or not, the Iran deal is the only deal we’ll get

The landmark deal reached last year, where Iran agree to curtail its nuclear program in exchange for the lifting of economic sanctions, was a better resolution than Perry had expected to the negotiations, but it has met with significant resistance from groups he described as “strange bedfellows.”

“The opposition in Israel and the United States opposed the deal because they fear it will allow Iran to get a bomb,” Perry said.

“Whereas the opposition in Iran opposed the deal because they fear it will prevent Iran from getting a bomb. Both cannot be right.”

Many Republican presidential hopefuls have publicly stated on the campaign trail that they would withdraw from the deal if they got elected to the White House, but Perry said that would be a strategic mistake.

“The opposition in the United States has a simple formula – we should withdraw from the deal, we should reinstate sanctions, and we should renegotiate a better deal,” Perry said.

“Let me be as blunt as I can, this is a pure fantasy. There is not the remotest possibility that the sanction could be reapplied if the United States withdraws from this deal, because the day we withdraw from the deal, our allies are gone, the sanctions are gone, there will be no renegotiations without sanctions, so this deal, like it or not, is the only deal we will ever get.”

Another “Mumbai” attack could spark regional nuclear war

Nuclear rivals India and Pakistan have more than a hundred nuclear weapons on each side, as well as the missiles to deliver them, and a conventional military conflict between them could quickly escalate into a regional nuclear war, Perry said.

Another large-scale terror attack, like the coordinated assault in Mumbai that killed more than 163 people in 2008, could lead India to retaliate militarily against Pakistan (which India blames for encouraging the terror groups operating in Pakistani territory).

Perry said he was concerned that Pakistan would then use tactical nuclear weapons against invading Indian troops, and that India might then respond with a nuclear attack of its own on Pakistan.

“So this is the nightmare scenario of how a regional nuclear war could start,” Perry said.

“A nightmare that would involve literally tens of millions of deaths, along with the possibility of stimulating a nuclear winter that would cause widespread tragedies all over the planet.”

A ray of hope

Despite all the potential for nuclear disaster in the current geopolitical environment, Perry said he was still hopeful that nuclear catastrophe could be avoided.

"While much of my talk today has a doomsday ring to it, that truly is not who I am,” Perry said.

“I’m basically an optimist. When I see a cloud, I look for a ray to shine through that cloud.”

One important step toward reducing the nuclear threat would be improving relations between the U.S. and Russia, he said.

“My ray of sunshine, my hope, is I believe we can still reverse the slide in U.S. Russia relations, he said.

“We must begin that by restoring civil dialog. We must restore cooperation between the United States and Russia in areas where we have mutual interest…If we succeed in doing that, then we can work to stop and reverse the drift to a greater and greater dependence on nuclear weapons.”

Perry ended his speech by urging the audience to keep striving to rid the world of the threat of nuclear weapons.

“We must pursue our ideals in order to keep alive our hope – hope for a safer world for our children and for our grandchildren,” he said.

Stanford researchers working with the U.S. Navy’s Marine Mammal Program in San Diego have discovered a startling variety of newly-recognized bacteria living inside the highly trained dolphins that the Navy uses to protect its ships and submarines, find submerged sea mines and detect underwater intruders. They found similar types of bacteria in wild dolphins as well.

“About three quarters of the bacterial species we found in the dolphins’ mouths are completely new to us,” said David Relman, Stanford professor of microbiology and medicine, and co-author of a paper published in the journal Nature Communications on Wednesday.

A U.S. Navy dolphin opens its mouth for a swab to collect bacterial samples.

“Bacteria are among the most well-studied microbes, so it was surprising to discover the degree to which the kinds of bacteria we found were types that have never been described,” he said. “What novelty means is not just new names of species, families, classes or phyla…there’s reason to believe that along with this taxonomic novelty, there’s functional novelty.”

The U.S. Navy has been training dolphins and sea lions to carry out defensive military missions from their bases in San Diego and elsewhere since the early 1960s.

Over the years, it has also funded scientific research and become the single largest contributor to the scientific literature on marine mammals, producing more than 800 publications, according to the Navy.

Relman started working with the Navy more than 15 years ago to identify bacteria suspected of causing stomach ulcers in their dolphins.

His latest project to catalog the bacterial communities (or microbiota) living inside the dolphins began when the Navy asked him to help develop a probiotic bacterial strain that could keep their dolphins healthy, or help sick dolphins get better.

Navy trainers took regular swabs from the dolphins’ mouths and rectal areas, using what looked like a Q-tip, and shipped the samples to Stanford on dry ice for analysis.

Stanford researchers analyzed oral, rectal and gastric samples from the U.S. Navy's dolphins and sea lions, as well as samples from the dolphins' blowholes and the surrounding water.

The study found a similar amount of diversity and novelty in bacterial samples taken from wild dolphins living in Sarasota Bay off the west coast of Florida, although there were slight differences in the bacteria from the dolphins’ mouths.

Relman said he hoped to develop a profile of the normal microbial communities in healthy dolphins and other marine mammals, so that scientists could detect any early change that might signify an imminent disease, or health problems caused by climate change and ocean warming.

“There’s a lot of concern about the changing conditions of the oceans and what the impact could be on the health of wild marine mammals,” Relman said. “We would love to be able to develop a diagnostic test that would tell us when marine mammals are beginning to suffer from the ill effects of a change in their environment.”

The research could help solve other mysteries, such as how dolphins digest their food, even though they swallow fish whole without chewing them.

The key could be a unique bacterial group that’s also been identified in an endangered species of freshwater dolphins living in China’s Yangtze River, said Elisabeth Bik, a research associate at the Stanford Department of Medicine and lead author on the paper.

“It’s a very intriguing bacterial group that nobody has seen before in any other terrestrial animal group,” said Bik. “I would really love to know more about those bacteria and sequence their genomes to understand more about their functional capacity.”

Zak, a 375-pound California sea lion, shows his teeth during a training swim. Zak has been trained to locate swimmers near piers, ships, and other objects in the water considered suspicious and a possible threat to military forces in the area.

“The sea lions and dolphins are kept at the same facility, they’re fed exactly the same fish, and they’re swimming in the same water…but they’re very, very different in terms of microbiota,” Bik said.

Unlike dolphins, sea lions share many common types of bacteria with their terrestrial cousins.

“Sea lions weren’t that different from other carnivores like dogs and cats,” Bik said. “They’re evolutionarily related to them, and their microbiota looks very similar to those animals. But dolphins don’t really have a terrestrial mammal that’s closely related, and their microbiota looks very different from anything else that people have seen.”

Relman said his team was planning on expanding their study to include other marine mammals such as sea otters, killer whales, baleen whales, grey whales, harbor seals, elephant seals and manatees. Their purpose, in part, is to understand how life in the sea, over the millions of years since the return of mammals, may have shaped the structure of their microbial communities and the roles they play in marine mammal health.

They’re already working to analyze more than 80 samples of killer whale stool that the U.S. National Oceanic and Atmospheric Administration has gathered with the help of specially trained sniffer dogs, which stand on the bow of their boats and point to fresh killer whale feces before it sinks.

The California Department of Fish and Wildlife is contributing samples from the sea otters and seals it studies as part of its conservation, ecological, and monitoring programs.

And the Marine Mammal Center in Sausalito, which is the West Coast’s largest rescue and rehabilitation facility for marine mammals, is sending samples from the seals in its care.

Relman said the research could help scientists begin to answer fundamental questions about life in the ocean.

“Marine mammals remain one of the more poorly understood habitats for studying microbial life, and there would be lots of reasons for thinking that these are important environments to study, in part because of the relevance for the health of these marine mammals, but also because they represent a view into what it means to live in the sea and the nature of our relationship with this vast aspect of our environment,” Relman said.

Collaborators and co-authors on this study included Stephanie Venn-Watson and Kevin Carlin from the National Marine Mammal Foundation, and Eric Jensen from the Space and Naval Warfare Systems Center Pacific, in San Diego.

The world remains perilously close to a nuclear disaster or catastrophic climate change that could devastate humanity, according to Stanford experts and California Governor Jerry Brown, who were on hand to unveil the latest update to the Bulletin of Atomic Scientists’ “doomsday clock” on Tuesday.

The symbolic clock was created in 1947 when Albert Einstein and Robert Oppenheimer (the father of the U.S. nuclear program) founded the publication.

The closer the minute hand gets to midnight, the closer their Board of Science and Security predicts humankind is to destroying itself.

“I must say with utter dismay that it stays at three minutes to midnight,” said Rachel Bronson, the publication’s executive director and publisher, in a bi-coastal teleconference carried live from The National Press Club in Washington D.C. and the Stanford campus.

Despite some positive development over the past year, such as the Iran nuclear deal and the Paris climate accords, the doomsday clock is now the closest it’s been to midnight since the peak of Cold War hostilities in the mid 1980s.

Stanford experts, including former U.S. Secretary of Defense William J. Perry and former Secretary of State George P. Shultz, said they agreed with the dire assessment.

“The danger of a nuclear catastrophe today, in my judgment, is greater than it was during the Cold War…and yet our policies simply do not reflect those dangers,” said Perry, who is a faculty member at Stanford’s Center for International Security and Cooperation.

Perry said he was especially concerned that the U.S. and Russia were engaged in new arms race, with both countries working to rapidly modernize their nuclear arsenals.

“Whatever we need to do for deterrence, it does not require rebuilding what we did during the Cold War era,” he said.

Perry urged President Barack Obama not to give up on the goal of nuclear disarmament during his last year in office, and to push for a breakthrough deal to control fissile material at the upcoming Nuclear Summit in Washington D.C.

“These summit meetings have been quite significant, and if he can use this last summit meeting to establish international standards for fissile control, which fifty heads of state sign up to, that would be a real achievement,” Perry said.

Shultz said the U.S. needed to offer a new version of the bold plans and decisive actions that legendary American statesmen George Marshall and Dean Acheson pursued after World War II.

“We have to be engaged, because when we don’t give leadership, nobody does,” said Shultz, a distinguished fellow at the Hoover Institution.

The doomsday clock was initially designed to communicate the threat from nuclear weapons, but has since been expanded to include cyber and biosecurity and the dangers of unsustainable climate change.

California Governor Jerry Brown described climate change as a “daunting threat,” with many similarities to nuclear dangers.

“Climate change and nuclear accident or nuclear war or nuclear sabotage or nuclear terrorism, they’re tied together,” Brown said.

“Climate change is moving slowly, but tipping points are around the corner and you don’t know when you’ve reached one, and beyond a tipping point, we may not be able to come back.”

Brown said he was dismayed at the lack of political action to address climate change and nuclear threats.

“I’ve been around politics all my life, and I can see an obviously broken process, a democratic system that has turned more into spectacle than getting the job done,” Brown said.

“In order to have the political leaders deal with this, they have to first acknowledge it.”

When a high school student in the audience asked what he could personally do to tackle the threat of nuclear weapons, Perry said the most important step was to educate himself about the issues, so he could educate others.

“If you can get ten people interested in talking about this problem, and each of those ten can get ten people interested in talking about this problem, it builds up in a geometric progression,” Perry said.

“I think once the public understands the dangers, they will galvanize our Congress and our leaders into action.”