The Bulletin of the Atomic Scientists advanced the symbolic Doomsday Clock a notch closer to the end of humanity Thursday, moving it ahead by 30 seconds after what the organization called a “grim assessment” of the state of geopolitical affairs.

“As of today,” Bulletin president Rachel Bronson told reporters, “it is two minutes to midnight” — as close as the world has ever been to the hour of apocalypse.

In moving the clock forward, the group cited “the failure of President Trump and other world leaders to deal with looming threats of nuclear war and climate change.”

The organization — which has 15 Nobel laureates on its board — now believes “the world is not only more dangerous now than it was a year ago; it is as threatening as it has been since World War II,” Bulletin officials Lawrence M. Krauss and Robert Rosner wrote in an op-edpublished Thursday by The Washington Post. “In fact, the Doomsday Clock is as close to midnight today as it was in 1953, when Cold War fears perhaps reached their highest levels.”

The last time the clock advanced so far, the United States had just tested its first thermonuclear device, and the Soviet Union had tested a hydrogen bomb.

Today, said the Bulletin president Bronson, “to call the world’s nuclear situation dire is to understate the danger and its immediacy.”

At a news conference Thursday, Bronson and a group of colleagues that included Krauss and Rosner listed a litany of grim developments over the past year: North Korea made rapid progress in developing a thermonuclear weapon capable of reaching the United States. Relations between the United States and Russia deteriorated, with no high-level arms control negotiations happening between the two countries. Nations around the world have moved to modernize and enhance their nuclear arsenals.

Meanwhile, Trump and North Korean leader Kim Jong Un have engaged in a my-nuclear-button-is-bigger-than-yours war of words.

“There is little doubt that the risk that nuclear weapons may be used — intentionally or because of miscalculation — grew last year around the globe,” Rosner said.

The decision to move the clock forward was motivated largely by the Bulletin's sense of looming nuclear peril. But the danger is compounded by humanity's continued inaction on climate change, they said, as well as vaguer concerns about unchecked artificial intelligence, the spread of disinformation, and the public's eroding trust in institutions that could keep these threats at bay.

The clock, a metaphorical measure of humankind's proximity to global catastrophe, also advanced 30 seconds last year, to 2½ minutes to “midnight.”

Even before Thursday's announcement, experts said there was only one direction the clock could possibly move, given recent events.

“I think it would be very hard for the clock not​ to move forward,” said Alex Wellerstein, who specializes in the history of nuclear weapons at the Stevens Institute of Technology. “We have members of Congress, White House advisers, and even the president implying that they think war with a nuclear state is not only likely, but potentially desirable. That's unusual and disturbing.

“The question I have is: How much forward can they go?”

Another 30 seconds, to be exact.

The clock is symbolic, sitting at the intersection of art and science, and it has wavered between two and 17 minutes until doom since its inception in 1947.

The Bulletin of the Atomic Scientists was founded by veterans of the Manhattan Project concerned about the consequences of their nuclear research. One of them, nuclear physicist Alexander Langsdorf, was married to artist Martyl Langsdorf, who created the clock and set it at seven minutes to midnight, or 11:53, for the cover of the group's magazine. Her husband moved the time four minutes ahead in 1949.

Since then, the Bulletin's board has determined when the clock's minute hand will move, usually to draw attention to worldwide crises that it believes threaten the survival of the human species.

“Whenever the clock is set, we answer two basic questions,” Bronson said in an interview in the fall. “Is the world safer, or at greater risk than it was a year ago? And is it safer or at greater risk than it was ever in the clock’s history?”

The group's reasoning has traditionally focused on the availability of nuclear weapons and a willingness among the world's great powers to use them. But in recent years, the scientists have also considered the threat posed by climate change, which they said in 2007 is “nearly as dire” as the dangers of nuclear weapons.

In advancing the famed clock last year, the group noted that “the global security landscape darkened as the international community failed to come effectively to grips with humanity’s most pressing existential threats, nuclear weapons and climate change.”

But the organization also cited the election of Trump — “who has promised to impede progress on both of those fronts,” Krauss and retired Navy Rear Adm. David Titley wrote in an op-ed last year. “Never before has the Bulletin decided to advance the clock largely because of the statements of a single person. But when that person is the new president of the United States, his words matter.”

Daryl Kimball, executive director of the nonprofit Arms Control Association, said a symbolic move toward “midnight” makes sense — and that nuclear risks alone justified it.

“Over the year, there has been increased tensions with North Korea, nuclear threats conveyed by President Trump and Kim Jong Un, tensions with Russia are higher — perhaps as difficult as they have been since the end of the Cold War,” he said Wednesday. Within days, Kimball noted, the Trump administration is set to announce a nuclear strategy that calls for expanding the role of U.S. nuclear weapons. “So the risk of a nuclear conflict by accident or by design is unfortunately growing higher,” he added.