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Former US Secretary of Defense Chuck Hagel has criticised the Obama administration for lacking an overarching policy on Syria.

In an interview with Foreign Policy magazine (FP), Mr Hagel described long, tedious policy meetings that often concluded without decision.

The moderate Republican served as Mr Obama's defence chief for two tumultuous years from 2013 to 2015.

His tenure ended, he said, with backstabbing and character destruction.

Mr Hagel believes that a coherent US strategy for Syria still has not been fleshed out.

"The administration is still struggling with a political strategy, but Secretary Kerry is making some progress toward the right strategy," Mr Hagel tells the magazine, in reference to talks with Russian, Iranian and Arab leaders.

Mr Hagel's tenure in the Obama administration was marked by contention from the start.

Analysis: Tara McKelvey, BBC White House Correspondent

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Some of Mr Hagel's criticisms come across as minor or personal. "There were way too many meetings" at the White House, he says. And people there said mean things about him behind his back, "vilifying me in a gutless, off-the-record kind of way".

But his criticism of Mr Obama's strategy towards Syria and the fight against the Islamic State group is sharp - and is likely to resonate. In short, says Hagel: "We don't have a policy."

As Washington prepares to enter another election campaign, his remarks will provide fellow Republicans with yet more proof - from a trusted insider- that Mr Obama is a weak leader without a Middle East strategy.

Among those Mr Hagel had the worst relationship with was National Security Advisor Susan Rice.

He alleged that meetings chaired by Ms Rice, were long, frequent and fruitless.

"We kept kind of deferring the tough decisions. And there were always too many people in the room," he is quoted as saying.

He contrasted these meetings with those run by President Barack Obama, which he said were more effectual.

Image copyright The White House Image caption Mr Hagel was critical of Ms Rice (far left) and the Obama administration's Syria policy

However, Mr Hagel seemed to be most critical of Mr Obama's Syria policy.

Joining his boss in opposing a large troop deployment to Syria or Iraq, he insisted however on a clearer diplomatic stance.

In particular, he pointed to an embarrassing Senate hearing, where he was grilled over whether the US would defend the rebels it was training and equipping in Syria from attacks by Assad forces.

"We had never come down on an answer or a conclusion in the White House," Mr Hagel told FP. "I couldn't say 'No'. Christ, every ally would have walked away from us in the Middle East".

In a memo penned a month later, Mr Hagel called on the administration to formulate a clearer policy. He said memo was not well received.

A month later, Mr Obama accepted his resignation amid reports of differences over policy.

Some have suggested that those antagonistic relationships may have led to Mr Hagel being pushed out.

The White House has declined a BBC request for comment on this story.