Chief of staff becomes sixth Pentagon official to quit within a month

Move comes as top military officials 'stunned' by Donald Trump's decision to kill Qassem Soleimani

The chief of staff to the US defence secretary is standing down – the sixth senior civilian Pentagon official to leave their post in recent weeks.

Eric Chewning, the right hand man to Mark Esper, will end his job at the end of the month.

Reports suggest he will be replaced by Jen Stewart, the top Republican member of staff on the House Armed Services Committee, and a former adviser to the chairman of the Joint Chiefs.

“I’m grateful for Eric’s professionalism, judgment, and leadership over the last seven months as I moved into the secretary of defence role,” Mr Esper said in a statement.

“In an incredibly demanding job, Eric has been a source of calm and tireless work. He will be missed by all. We wish him all the best upon his return to the private sector.”

Politico, which was the first to report the news, did not suggest Mr Chewning’s departure was in any way linked to Donald Trump’s decision to order the targeted killing of Iranian military leader Qassem Soleimani.

It is known, however, the option of killing the Quds Force leader was among the “extreme” options presented to Mr Trump when asked for options on how to respond to the killing of a US contractor by a rocket attack on a base in Iraq by Iraqi militia.

Reports said Mr Trump first chose to respond by attacking five militia bases. But when he subsequently saw attacks on the US embassy in Baghdad by Iran-backed militia members, he decided to order the strike on Soleimani.

The New York Times said that “top Pentagon officials were stunned”.

Fox News said Mr Chewning’s departure had been expected, and claimed it was not related to the current Iranian conflict.

However, Mr Chewning, who is said to be joining the private sector, is the latest in a succession of senior civilians to depart the defence department.

Among those who have also left was director of Defence Advanced Research Projects Agency, the acting undersecretary for personnel and readiness, the principal deputy undersecretary for intelligence, and the assistant secretary for Asian and Pacific security affairs.