President Barack Obama (right), standing with Defense Secretary Chuck Hagel, talks about Hagel's resignation during an event in the State Dining Room of the White House in Washington this morning. - AP
The US media is reporting that Chuck Hagel will resign as US defence secretary after less than two years in the top US military post.
Hagel, who is a 68-year-old Vietnam war veteran and former senator, became defence secretary in 2013.
He is reportedly stepping down amid a shift in US military strategy to fight Islamic State (IS).
Hagel is expected to stay on as secretary until his successor is confirmed.
An unnamed official told the Associated Press news agency that Hagel and US President Barrack Obama both "determined that it was time for new leadership in the Pentagon" and had been discussing the move for weeks.
