President Donald Trump’s decision to depart Turkey on an older plane while sending his new, Qatari-gifted jet ahead to England was driven at least in part by security concerns around the escalating conflict in Iran, according to four US officials.

Two of the officials said security personnel felt more comfortable with the president aboard the older vessel — which was built from scratch with the commander-in-chief’s safety in mind — rather than the plane that had recently been retrofitted after it was donated by Qatar.

While sources said there was no specific, new threat to Trump’s life, the president had mentioned the possibility of an assassination attempt from Iran during the NATO summit, following fresh US strikes on the country that shares a border with Turkey.

“I’m number one on the list for killing,” he said.

The New York Times previously reported on the security concerns. CNN has reached out to the White House for comment.