Richard M. Nixon told advisers during the Vietnam War that he wanted the North Vietnamese to believe he was an unpredictable “madman” who could not be restrained “when he’s angry, and he has his hand on the nuclear button.”
During the 2016 presidential election, Hillary Clinton said of her opponent, “Trump shouldn’t have his finger on the button, or his hands on our economy.”
How would President Trump launch an attack?
Each nuclear-capable country has its own system for launching a strike, but most rely on the head of government first confirming his or her identity and then authorizing an attack.
Despite Mr. Trump’s tweet that he has a “much bigger & more powerful” button than Mr. Kim, the fact is, there is no button.
There is, however, a football. Except the football is actually a briefcase.
The 45-pound briefcase, known as the nuclear football, accompanies the president wherever he goes. It is carried at all times by one of five military aides, representing each branch of the United States armed forces.
Inside the case is an instructional guide to carrying out a strike, including a list of locations that can be targeted by the more than 1,000 nuclear weapons that make up the American arsenal. The case also includes a radio transceiver and code authenticators.
To authorize the attack, the president must first verify his identity by providing a code he is supposed to carry on him at all times. The code, often described as a card, is nicknamed “the biscuit.”
In his 2010 autobiography, Gen. Henry H. Shelton, chairman of the Joint Chiefs of Staff during the final years of Bill Clinton’s presidency, wrote that Mr. Clinton had lost the biscuit for several months without informing anyone.
“That’s a big deal,” General Shelton wrote, “a gargantuan deal.”
The president does not need approval from anyone else, including Congress or the military, to authorize a strike — a decision that might have to be made at a moment’s notice.
Nevertheless, some politicians have called for more layers of approval.
“The longer I’m in the Senate, the more I fear for a major error that somebody makes,” Senator Dianne Feinstein, Democrat of California, said in 2016. “One man, the president, is responsible. He makes an error and, who knows, it’s Armageddon.”
How would Kim Jong-un order a strike?
Much of North Korea’s nuclear program is shrouded in mystery.
Mr. Kim, however, is the undisputed ruler of his isolated country. Any decision to initiate an attack would most likely be his alone. In recent months, Mr. Kim has threatened to ignite an “enveloping fire” of missiles near the Pacific island of Guam, an American territory, and has warned that North Korean intercontinental ballistic missiles are capable of reaching the mainland United States.
“It’s not a mere threat but a reality that I have a nuclear button on the desk in my office,” Mr. Kim said in a speech on Monday. “All of the mainland United States is within the range of our nuclear strike.”
It is doubtful that there really is a button on his desk. Furthermore, an intercontinental attack from the North probably could not happen in minutes, let alone seconds.
The North’s longest-range missiles are believed to be powered by liquid rocket fuel. That means the missiles cannot be stored and ready-to-fire at a moment’s notice. They must be loaded with fuel before launch, a process than can take hours.
Newer, shorter-range missiles, are loaded with solid fuel, however, making them easier to launch before the North’s enemies detect an attack.