Nancy Pelosi spoke to the head of the US military on Friday, seeking assurance that Donald Trump will not be able to launch a nuclear strike during his last days in office. At the end of a bizarre and dangerous week in which the US Capitol was stormed by supporters of the president, in an attack that left five people dead and prompted widespread calls for his immediate removal, the House speaker told Democrats she had called Gen Mark Milley, the chairman of the Joint Chiefs of Staff. Amid rising tensions with Iran and other foreign policy challenges, Pelosi sought to “to discuss available precautions for preventing an unstable president from initiating military hostilities or accessing the launch codes and ordering a nuclear strike”. A spokesman for Milley confirmed the conversation. “Speaker Pelosi initiated a call with the chairman,” the spokesman said. “He answered her questions regarding the process of nuclear command authority.” Trump remains commander-in-chief of the US armed forces. Before the storming of the Capitol on Wednesday, all 10 former defense secretaries still living had called for the military to stay out of the transition of power. Five people including a Capitol police officer died as a result of the assault on the Capitol, which occurred after Trump addressed supporters about his attempts to overturn his defeat by Joe Biden and encouraged them to “fight like hell”. Rioters broke into the House and Senate chambers and offices including that of Pelosi. Regardless, Republicans in both chambers moved ahead with objections to Trump’s electoral college defeat. The objections were defeated. Democrats called for Mike Pence and members of the cabinet to invoke the 25th amendment, which provides for the removal of a president deemed unfit for office. Such a move would put Trump out of power until inauguration day, 20 January, even if he contested it. In a statement on Thursday, Pelosi said: “The president’s dangerous acts necessitate his immediate removal from office. We look forward to hearing from the vice-president as soon as possible and to receiving a positive answer as to whether he and the cabinet will honour their oath to the constitution and to Americans.” But the idea is seen as a non-starter, not least as the transportation secretary, Elaine Chao, has led what could be multiple cabinet resignations. Influential sources including the editorial page of the Wall Street Journal have called on Trump to resign. On Friday, Pelosi said House Democrats would otherwise move towards a second impeachment. Trump was acquitted in the first last February, over approaches to Ukraine for dirt on Biden, after a short trial in the Republican-held Senate. Informing Democrats of her conversation with Gen Milley, Pelosi wrote: “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 also said she and the Senate minority leader, Chuck Schumer, had not heard back from Pence. “We still hope to hear from him as soon as possible with a positive answer,” Pelosi wrote. “Nearly 50 years ago, after years of enabling their rogue president, Republicans in Congress finally told President [Richard] Nixon that it was time to go. Today, following the president’s dangerous and seditious acts, Republicans in Congress need to follow that example and call on Trump to depart his office – immediately.” Some Republicans in Congress, representatives Adam Kinzinger and Steve Stivers among them, have done so, as have Maryland’s governor, Larry Hogan, and Colin Powell, the former general and secretary of state who remains a party grandee. In the Senate, Ben Sasse of Nebraska indicated support for impeachment. The House minority leader, Kevin McCarthy, however, said on Friday he opposes a second impeachment, as it would “only divide our country more”. Nonetheless, Pelosi said: “If the president does not leave office imminently and willingly, the Congress will proceed with our action.”