All 10 former US defence secretaries still living, including two who worked for Donald Trump, have called for the president and his supporters to accept he lost the e******n and warned against attempts to involve the military in his increasingly desperate efforts to overturn the result.

In an unprecedented joint letter published in the Washington Post, the defence secretaries addressed the worst fears of what could happen in 17 days of Trump’s administration remaining before Joe Biden’s inauguration: an attempt by Trump to foment a crises with the aim of triggering a military intervention in his last-ditch struggle to hold on power.

“Efforts to involve the US armed forces in resolving e******n disputes would take us into dangerous, unlawful and unconstitutional territory,” the letter said.

“Civilian and military officials who direct or carry out such measures would be accountable, including potentially facing criminal penalties, for the grave consequences of their actions on our republic.”