Want smart analysis of the most important news in your inbox every weekday along with other global reads, interesting ideas and opinions to know? Sign up for the Today's WorldView newsletter.

President-elect Donald Trump becomes President Trump on Friday. That will give him control over the United States' arsenal of close to 1,400 active nuclear warheads — that is, warheads affixed to ballistic missiles or placed inside bombs at American air bases.

For critics of Trump, this is a terrifying proposition. The thought of a politician as unpredictable as the new president with his finger on the proverbial nuclear button (there is no actual button) is prompting an unprecedented level of panic in Washington.

In October, a letter signed by 10 former nuclear launch officers warned that Trump was ill-suited for the task of commander-in-chief.

"The pressures the system places on that one person are staggering and require enormous composure, judgment, restraint and diplomatic skill," the statement read. "Donald Trump does not have these leadership qualities. On the contrary, he has shown himself time and again to be easily baited and quick to lash out, dismissive of expert consultation and ill-informed of even basic military and international affairs — including, most especially, nuclear weapons."

One MSNBC journalist alleged in August that during an hour-long briefing on nuclear security Trump asked three times, "Why can’t we use nuclear weapons?" (My colleague Dan Zak wrote last year at length about the mechanics of ordering a nuclear launch; a military aide tails the president at all times with an aluminum briefcase — known euphemistically as the "football" — that contains what is basically a how-to "manual for conducting nuclear war.")

Since winning the election, Trump has made a number of alarming statements, including a tweeted call for an expansion of American nuclear capabilities and a suggestion he would welcome a nuclear arms race with Russia and other countries. Furious condemnation followed, sprinkled with utter bafflement that Trump would be willing to upend decades of bipartisan policy on nuclear weapons and international nonproliferation.

He later seemed to backtrack in an interview with two European publications published last weekend, suggesting "nuclear weapons should be way down."

For what it's worth, here's the state of play of the global nuclear arms race, per a chart compiled by the Arms Control Association:

Despite his backtracking, there are real reasons to be concerned about Trump and nuclear weapons.

Rick Perry, Trump's choice to run the Department of Energy, which monitors the American nuclear stockpile, is woefully under-equipped to preside over nuclear policy as compared to his predecessors. The former Texas governor spent a part of his hearing on Thursday apologizing for a call he made in 2012 to abolish the department altogether.

"On the basis of Governor Perry's complete lack of experience in dealing with the most devastating weapons in the world — the nuclear arsenal of the United States — we overwhelmingly object to his nomination to the position of Energy Secretary," said Mike Breen, the CEO of the Truman National Security Project, a network of policy wonks named after the only American president to use the atomic bomb. Perry demonstrated "an astounding lack of both intellectual depth and perspective for consequences," Breen said in an emailed statement.

The man Perry is tapped to follow, the conspicuously coiffed Ernest Moniz, is an acclaimed M.I.T. physicist. On his last day in office, Moniz's press staff shared a picture of their boss' overcrowded desk.

Neither Trump nor Perry can bring such heft to their jobs. Trump's publicized views on nukes are confused and likely not fully formed. "Don't treat these utterances as serious policy statements," tweeted one Washington-based nuclear security wonk.

But one thing is clear: Trump's penchant for militarism.

He obsesses over the projection of American strength. According to a source involved in inauguration planning who spoke to the Huffington Post, Trump seriously floated the idea of a full-fledged military parade with tanks and missiles. The Pentagon apparently said no, but will carry out a military flyover, the first at an inauguration since 1949.

Trump used his bully pulpit during the election campaign to threaten dramatic unilateral action in the world's war zones. But as president, he will have to be more careful. Already, as South Korean media reports, North Korea appears to be readying test launches of two ICBMs. It's a move also aimed at testing the cool of the new American president.

There's some hope that the gravity of Trump's new office will be sobering. All new American presidents are given a classified briefing where they are instructed on how to order a nuclear attack. In the past, as Politico's Michael Crowley noted, it has had a humbling effect on the men taking part.

Crowley cited the 1999 memoir of Bill Clinton's former spokesman George Stephanopoulos. "The man who would soon command the most powerful military force in the world emerged … silent and more somber than I’d ever seen him," Stephanopoulos wrote in reference to Clinton's first briefing. "Clinton wasn’t the only one moved," added Crowley. "Stephanopoulos recalled that George H.W. Bush’s outgoing national security adviser, retired Gen. Brent Scowcroft, 'slipped out of Blair House and into the street with tears reddening the rims of his eyes.'"

Will Trump have a similar reaction? That's anyone's guess, but experts urge that he at least refrain from firing off tweets at times of geopolitical stress (as he already has done).

"Imagine we’re in a crisis — if he recklessly tweets, people could read these things in the worst possible light," arms control expert Jeffrey Lewis told the Post last month. "The North Koreans have a plan to use nuclear weapons very early in a conflict. They’re not going to wait around. If they think we are going, they’re going to use nuclear weapons against South Korea and Japan."

"This is a very important issue," Bruce Blair, a nuclear policy specialist at Princeton University, told Post columnist Greg Sargent on Thursday. "Trump should and really must never tweet during moments of crisis."

Russia celebrates Trump — for now

"Trumpomania" has taken hold in the Russian capital ahead of Inauguration Day, the Post's David Filipov reports from Moscow, where many Russians are fired up as Donald Trump enters office. "Something about the advent of Trump has stirred the Russian soul," Filipov writes. “It’s almost as though the 45th president of Russia were about to take office on Friday."

Okay, perhaps it's a little over top — businesses are literally renaming themselves in Trump’s honor, Filipov reports — but you can understand some of the excitement. Many Russians viewed President Obama as someone who, at best, cared little for Russia. Meanwhile, his ordained Democratic successor in the Oval Office, Hillary Clinton, had a notoriously bitter relationship with Vladimir Putin.

But how long will the Russian love affair with Trump last? Already in the halls of Russian power there are signs that expectations are being tempered. The president-elect may still speak in relatively warm terms about Russia, but many of his cabinet picks do not. A number of confirmation hearings have turned into full-on Russia-bashings.

"There is a sensible shift of expectations in the Kremlin," Alexei Chesnakov, a former senior Kremlin staffer, told Bloomberg News in an interview. "The leadership understands clearly now that restoring ties won’t be easy and that more scandals will worsen the chances."

Sanctions may well be the sticking point. Despite Trump's talk, his administration may face severe difficulties in rolling back the sanctions imposed on Russia by the U.S. over the past few years — and a bill to impose even harsher sanctions has considerable bipartisan support.

At the World Economic Forum in Davos, some Russian officials hinted they are not banking on sanctions being lifted. "We have adjusted not only to low oil prices but also sanctions," Maxim Oreshkin, Russia's minister of economic development, said at the gathering.

The truth, however, is more complicated. Russia's domestic situation may not be as stable as it seems. One poll published this week found 45 percent of the country was dissatisfied with the situation in Russia — and that discontent in the country seemed to be growing. Putin, who remains remarkably popular with Russians, has long been able to blame Russia's woes on Washington. With presidential elections coming in 2018, would he really be willing to give that up? — Adam Taylor

Want smart analysis of the most important news in your inbox every weekday along with other global reads, interesting ideas and opinions to know? Sign up for the Today's WorldView newsletter.