Michael Flynn resigns: Who will Trump hire to replace him as national security adviser?
US president Donald Trump is charged with picking his second national security adviser less than a month into office after the embarrassment of Michael Flynn's resignation.
Flynn quit the post after reportedly misleading colleagues about his contacts with Russia, making his reign in the vital White House role the shortest in history.
Three men have emerged as the top contenders to replace him.
Keith Kellogg
The retired lieutenant general has emerged as as the effective frontrunner after Trump named him as the acting national security adviser.
Kellogg advised Trump - alongside Flynn - during his presidential campaign on national security and foreign policy issues before being named the National Security Council chief of staff when Flynn earned the more senior post.
Kellogg's most prominent previous role was as chief operating officer of the Coalition Provisional Authority in Iraq, the interim governing body installed after the overthrow of Saddam Hussein in 2003.
He had previously worked as an executive for an IT firm contracted to defence, intelligence and security agencies.
David Petraeus
The former CIA director and retired four-star general was considered for the post of secretary of state before the role when to Exxon chief Rex Tillerson.
His return to public life would be controversial given he left the intelligence agency under a cloud in 2012.
Petraeus left the role after only a year when it was revealed he passed classified information to his biographer, with whom he was having an extra-marital affair.
He branded Trump the "disruptor-in-chief" ahead of his inauguration last month.
Robert Harward
The retired vice admiral and ex-Navy Seal is a former deputy commander of the US Central Command.
Harward served on the National Security Council during George W. Bush's time in the White House and commissioned the National Counter Terrorism Centre.
He retired from the Navy in 2013 after almost four decades to lead UAE-based defence and aerospace giant Lockheed Martin.
Trump has recently been in very public negotiations with Lockheed over the cost of its F-35 fighter jet programme.