US President Donald Trump has sworn in his new chief of staff John Kelly.
Mr Kelly replaces Reince Priebus, who had grappled with infighting during his six months in the job and had been involved in a feud with Mr Trump's new communications director Anthony Scaramucci.
Mr Trump praised Mr Kelly for avoiding controversy during his tenure at the Department of Homeland Security.
He also credited Mr Kelly with reducing the number of people illegally crossing the southern US border with Mexico, and for implementing a travel ban for refugees and people from several majority Muslim countries.
"He will do a spectacular job, I have no doubt, as chief of staff," Mr Trump said after Mr Kelly was sworn in.
He added: "With a very controversial situation, there's been very little controversy, which is really amazing by itself."
Mr Trump did not give any details about how Mr Kelly would organise his White House, where until now several key advisers have reported directly to the president rather than to the chief of staff.
"We're doing very well, we have a tremendous base, we have a tremendous group of support. The country is optimistic, and I think the general will just add to it," he said.
Mr Kelly, a retired Marine Corps general, was brought in by Mr Trump after a chaotic week in which his first legislative effort - healthcare reform - failed in Congress, heightening concerns in the Republican Party that dysfunction would derail other priorities like tax reform.
