America’s and Britain’s top military officials fear the tide of the Syrian civil war is shifting in the regime’s favor.

Both America’s and Britain’s top military officials on Thursday bluntly assessed the Western countries’ inability to influence the outcome in Syria’s civil war which has dragged on for more than two years despite leaders’ calls on its embattled president Bashar Assad to step down.

General Sir David Richards, whose tenure as the United Kingdom’s chief of the defense staff expired this week, admitted that a lack of international consensus and splits within Syria’s rebel forces made a military solution difficult. He added, “the United Kingdom won’t do anything by itself. It will act with allies, in particular with the USA.”

His American counterpart General Martin Dempsey, the chairman of the Joint Chiefs of Staff, told Congress the same day that the United States government was considering military plans — possibly missile strikes against regime infrastructure, including chemical weapons sites, enforcing a no-fly zone or attacking with rebel groups who are linked to Al Qaeda with unmanned aerial vehicles — but admitted that the tide of the war seemed to have shifted in Assad’s favor.

Last year, Dempsey cautioned against military intervention by outside powers, contrasting Syria to Libya where Arab and Western countries enforced a no-fly and conducted airstrikes against the armed forces of Colonel Muammar Gaddafi which succeeded in toppling him.

“It’s a different challenge,” he told CNN, “geographically. It’s a different challenge in terms of the capability of the Syrian military.”

He also cautioned against arming Syrian opposition fighters at the time, saying, “I think it’s premature to take a decision to arm the opposition movement in Syria because I would challenge anyone to clearly identify for me the opposition movement in Syria at this point.”

President Barack Obama announced last month that the United States would start providing small arms to the rebels, after rejecting calls to interfere in the conflict for two years. But many lawmakers are skeptical and might block such efforts.

It was reported yesterday that Britain had abandoned plans to send weapons into Syria, lacking popular support for such intervention and concerned the insurgency is increasingly radicalized. While loyalist forces have been bolstered by support from the Lebanese militant group Hezbollah, Kurdish and secular opposition groups were outraged last week by the assassination of a rebel commander by Islamists who may be a minority of the fighters but do appear to have been the most successful in sustaining the insurgency.

Western allies in the region, notably Qatar and Saudi Arabia, have armed Syrian rebels, possibly in collusion with nearby Jordan and Turkey, hoping that they will topple Assad who is the only Arab ally of their nemesis Iran. European powers and the United States have limited themselves to providing “nonlethal” aid, including communication and sanitation systems as well as body armor.