Two days after President Donald Trump roused supporters to raid the U.S. Capitol, House Speaker Nancy Pelosi asked the Pentagon’s highest military officer about the processes involved in ordering a nuclear strike, Time reports.

Pelosi wrote a letter Friday to fellow lawmakers informing them that she spoke with General Mark A. Milley, the chairman of the Joint Chiefs of Staff, about keeping “an unstable President from initiating military hostilities or accessing the launch codes and ordering a nuclear strike.”

The phone call, which was confirmed by Milley’s office, comes as Pelosi moves to impeach Trump for a second time. “The situation of this unhinged President could not be more dangerous, and we must do everything that we can to protect the American people from his unbalanced assault on our country and our democracy,” she wrote.

The truth is, however, there is nothing to be done: the U.S. President has sole launch authority over the country’s nuclear arsenal. The power has remained with the White House since President Harry Truman ordered dropping atomic bombs over Hiroshima and Nagasaki during World War II.

Indeed, there is a military aide who shadows the Commander in Chief day and night, carrying the black briefcase commonly referred to as the “nuclear football,” packed with attack options and other information needed in a national emergency. At any moment’s notice, Trump is legally empowered to order a nuclear attack with America’s arsenal of strategic bombers, missile-launching submarines and land-based intercontinental ballistic missiles.