AMMAN - The Syrian opposition reportedly feels badly let down by Washington's decision to do a deal with Moscow to eliminate Bashar Assad's chemical weapons but diplomats are warning the Syrian National Coalition that it risks losing Western support if it cannot adapt to new realities.

The rift that has alienated the Syrian opposition from the United States threatens to derail international efforts to end the two and a half year civil war, diplomatic and opposition sources said.

It comes as the war has turned into a something of a stalemate on the battlefield and the rebels had been looking to the United States to tilt the balance in their favor by intervening militarily to punish Assad for using chemical weapons.

The behind the scenes dispute, in which Saudi Arabia and Turkey appear to be siding with the opposition, developed last week as the United States and Russia made their deal to destroy Assad's chemical arsenal following a nerve gas attack on rebel areas of Damascus that killed hundreds, the sources said.

The agreement, from which the United States hopes a wider political settlement can emerge, has reduced the likelihood of a US strike on Assad's forces that the opposition had hoped would weaken him militarily and force him to attend a planned new peace conference.

The opposition is therefore furious that Washington suddenly and without its knowledge changed course a week after informing leaders of the main Syrian National Coalition that a strike was imminent, according to coalition members.

In the opposition's view, the deal with Russia contains a de facto admission of the legitimacy of the Assad government, undermining the goal of Syrian uprising and the likelihood that any peace talks will result in Assad's removal.

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