The US has warned Syria that the use of chemical weapons would cross a red line and result in "action". But what kind of action and how credible are the anonymous reports of Syria's weapons of mass destruction (WMD) anyway?

"What's changed is now a discussion of what was Obama's criteria for justifying an intervention in Libya: being on the edge of an atrocity. But you had to have a regional commitment for the move and essentially UN approval for the move. These are all part of a very well defined set of criteria the president's national security gave to me personally and said: 'This is how we've made our decision'."

- Steve Clemons, from The Atlantic magazine

On Wednesday, the US media reported that Syria's government had loaded precursor chemicals for Sarin nerve gas into bombs to target the country's opposition.

Syrian government officials have emphatically denied the reports, arguing that they are designed to provide a pretext for full-scale military intervention.

Leon Panetta, the US defence secretary, expressed his concerns and Hillary Clinton, the US secretary of state, promised "action" should such weapons be used. Though both refused to say exactly how the US would respond.

Amidst the reports of WMD, NATO moved forward with its plan to place Patriot missiles and troops along Turkey's border with Syria.

Also this week, anonymous US officials conceded to the New York Times that arms shipments approved by Washington to Libyan rebels from the Qatari government had been delivered to anti-American fighters.

It was a reminder of the potential for blowback should the US decide on more robust involvement in the Syrian conflict.

On Thursday, a reporter from the Associated Press queried the state department on its criteria and logic as it considered further intervention.

So, what is driving US policy towards Syria?

To discuss this Inside Story Americas, with presenter Shihab Rattansi, is joined by guests: Hillary Mann Leverett, a former White House and state department official; Steve Clemons, the editor-at-large for The Atlantic magazine; and Tony Karon, a senior editor at Time Magazine.

"We've been down this road before ... on the basis of so-called evidence which was really manufactured ... we went in to disarm him [Saddam Hussein] of weapons he didn't have and here nobody is asking the basic question: 'How do we know that chemical weapons are being mixed or moved that could be used in a way against their own people?' We honestly and probably have no way in knowing. This is not something you can get by flying a drone or getting your satellite to take pictures over a fortified bunker. These are things that go on inside a fortified bunker. By definition you need to have human intelligence to tell you what's going on and since we closed our embassy and left Syria, we have very little ability to get that human intelligence."

Hillary Mann Leverett, a former White House official

Source: Al Jazeera