Today, Trump attends "the classified briefing that explains how he can order a nuclear attack."

[Miles Archer]

By the time he is sworn in Friday, Donald Trump will have undergone a haunting rite of passage: the classified briefing given to every incoming president that explains how he can order a nuclear attack.

While neither U.S. nor Trump officials would confirm the exact time or location of Trump’s briefing, several past presidents have been briefed on the nuclear codes at the historic Blair House, on Pennsylvania Avenue near the White House, hours before their inauguration.

“It's a sobering moment. It defines the ultimate obligation that you might have,” said Andrew Card, who served as chief of staff to George W. Bush and was with Bush just before and after his first nuclear briefing in January 2001.

It is also likely sobering for millions of the Americans who heard a series of Trump rivals warn last year that the New York mogul must never gain access to America’s massive nuclear arsenal.

"How can you trust him with the nuclear codes?" President Barack Obama said at one October rally. "You can't do it."

http://www.politico.com/story/2017/01/donald-trump-nuclear-weapons-233822