What happens if Iran kills Trump? US has no ‘dead man’s switch', but Vance would make the call

US President Donald Trump is reportedly suggesting he has left standing orders for the US military to destroy Iran "at levels they've never seen before" if Tehran follows through on its long-standing threats to kill him.

But the US government has no way to create an automatic, preauthorised "dead man's switch" that would prompt immediate retaliation, the Associated Press reported.

Instead, if Trump were killed, the transfer of power to his successor is governed by the 25th Amendment and the Presidential Succession Act of 1947.

Vice President JD Vance would instantly become commander in chief and have authority for any retaliation.

Under such a scenario, Vance could do exactly what Trump called for, though there also is a chance he could decide not to follow his predecessor's orders - or offer a direct response in a different way.

"The US has, for a whole variety of reasons, never utilised a technical dead man's switch,'" said Garrett M. Graff, author of “Raven Rock: The Story of the U.S. Government's Secret Plan to Save Itself — While the Rest of Us Die.”

The United States does have extensive contingency plans for continuity of government in the event of a nuclear attack or other major catastrophe that wipes out most or all of Washington.

But those plans also do not allow for immediately launching retaliatory strikes upon the death of a president, even if that president had demanded that the military be ready to do so.

Iran's threat to assassinate Trump

Trump nonetheless posted on his social media website Saturday that Iran had made threats "to assassinate, or attempt to assassinate" him, and he said 1,000 "missiles are Locked and Loaded and aimed at the Islamic Republic of Iran, with thousands more to immediately follow, should the Iranian Government act on its threat."

Iran's supreme leader, Mojtaba Khamenei, said hours later that Iranians would continue to avenge the killing of his father, Ayatollah Ali Khamenei.

Ayatollah Ali Khamenei died in the initial US and Israeli strikes that started the war in late February, and he was mourned in funeral events throughout Iran this week. His son said retaliation "is the will of our nation and must certainly be carried out."

"We pledge to take revenge for the pure blood of you and all the martyrs of these two wars from the criminal and disgraceful killers," he said in remarks aired on state television. "This revenge is the will of our nation and must certainly be carried out."

During those recent funeral events, mourners repeatedly held posters or banners calling for Trump to be killed along with Israeli Prime Minister Benjamin Netanyahu.

The Wall Street Journal reported this week that Israel alerted US officials to fresh Iranian plots to kill Trump. The White House has refused to comment, but Trump appeared to reference such threats in comments during this week's NATO summit in Turkey, saying, "They want to take out the US leader - me."

Sabrina Singh, former Biden administration deputy Pentagon press secretary, said, "Iran wanting to target senior American leaders is something that we know is happening."

"You have to take these as credible threats," Singh said.

US retaliations would almost certainly come, just not automatically.

The White House on Saturday did not immediately answer questions about what would become of Trump's military orders should he be killed.

(With inputs from Associated Press)