(This post was last updated at 11:41 a.m. ET.)

Secretary of Defense Chuck Hagel, the highest-profile Republican on President Obama's Cabinet, will step down, once his successor is confirmed by the Senate.

Calling Hagel an "exemplary defense secretary," Obama made the announcement in the State Dining Room of the White House on Monday.

Hagel, a two-term Republican senator, came to the post in February of 2013, the first enlisted combat veteran to lead the Department of Defense.

The New York Times, which first reported the story, says Obama made the decision Friday after several meetings. The Times adds:

"The officials described Mr. Obama's decision to remove Mr. Hagel, 68, as a recognition that the threat from the Islamic State would require a different kind of skills than those that Mr. Hagel was brought on to employ. A Republican with military experience who was skeptical about the Iraq war, Mr. Hagel came in to manage the Afghanistan combat withdrawal and the shrinking Pentagon budget in the era of budget sequestration.

"But now 'the next couple of years will demand a different kind of focus,' one administration official said, speaking on the condition of anonymity. He insisted that Mr. Hagel was not fired, saying that he initiated discussions about his future two weeks ago with the president, and that the two men mutually agreed that it was time for him to leave."

The news comes just as American troops are completing their combat role in Afghanistan and just as the administration announced a new war against the Islamic State in Iraq and Syria.

Back in October, there were reports from CNN and the New York Times that described a memo written by Hagel in which he criticized the Obama administration's policy toward Syria.

Citing an unnamed senior U.S. official, CNN reported that Hagel told National Security Adviser Susan Rice that "we need to have a sharper view of what to do about the Assad regime."

Publicly, Hagel seemed in lockstep with the Obama administration. During congressional testimony earlier this month, Hagel said the administration's strategy against the Islamic State was making progress.

But he was sober about the mission to equip and train Syrian rebels.

"We know the opposition will continue to face intense pressure in a multifront battle space, and we are considering options for how U.S. and coalition forces can further support these forces once they are trained and equipped," Hagel said. "Our strategy in Syria will demand time, patience and perseverance to deliver results. We cannot accomplish our objectives in Syria all at once."

Update at 11:25 a.m. ET. An 'Exemplary Defense Secretary':

Announcing Hagel's resignation at the White House's State Dining Room, President Obama said he was an "exemplary defense secretary."

Obama said Hagel had deftly guided the military through a tough budgetary time and the drawdown in Afghanistan. Hagel, Obama said, also positioned the military to effectively deal with new threats like the one posed by the Islamic State.

As the first enlisted combat veteran to lead the Department of Defense, Obama said, Hagel "has been no ordinary secretary of defense."

"He sees himself in [service members] and they see themselves in him," Obama said.

Obama praised Hagel for always "giving it to me straight."

"We come from different parties," Obama said. "In accepting this position, you sent a powerful message ... that when it comes to national security, we are all Americans."

Hagel talked briefly. He thanked Obama and the military and redoubled his support for the president. He said serving as defense secretary was the "greatest privilege of my life."

"I will continue to support you, Mr. President, and the men and women who defend this country every day so unselfishly," Hagel said.

Update at 10:23 a.m. ET. A Surprise:

"Hagel was not seen as a very forceful secretary of defense," NPR's Tom Bowman tells Morning Edition. "We're told that in Cabinet meetings he really didn't say that much, but again this does come as a surprise that he's leaving this early."

Tom says Hagel disagreed with the White House because he wanted to take a harder line against the regime of Bashar Assad in Syria. But the White House was resistant to that kind of strategy.

Tom says there had been whispers that Hagel may not stay through the remainder of Obama's second term, but this sudden announcement comes as a surprise.

Copyright 2021 NPR. To see more, visit https://www.npr.org.