WASHINGTON (Reuters) - The United States is racing to finalize elements of its Syria strategy, planning new steps to shape and strengthen the still-fragmented opposition as signs build that the country is nearing a tipping point in the 20-month rebellion against President Bashar al-Assad.
Blocked at the United Nations by Russia and China, and wary of the growing influence of radical Islamists in the Syrian revolt, the Obama administration has forced a reorganization of the Syrian opposition into a new, broad coalition. It hopes the new coalition can secure stability after what U.S. officials regard as the inevitable collapse of the Assad government.
But with events moving quickly on the battlefield and world leaders warning Assad against resorting to his stockpile of chemical weapons as a last-ditch tactic, diplomatic analysts say Syria's crisis threatens to spin out of control before the U.S.-backed transition plan is in place.
"The horizon of the regime is quite a bit shorter than we imagined even three months ago, and I don't think the development of the opposition has kept pace," said Steven Heydemann, a Syria specialist at the U.S. Institute of Peace.
To accelerate the planning, Secretary of State Hillary Clinton will gather with allies and opposition representatives in the Moroccan city of Marrakesh next week. She is expected to announce that the United States recognizes the new coalition as "the legitimate representative" of the Syrian people - a symbolic endorsement of the group Washington hopes can mature into a transitional government.
The United States is also expected to offer more non-lethal aid to the rebels, while placing one of the most radical fighting groups, the al Qaeda-linked Nusra Front, on its blacklist of terrorist organizations. The action is meant to draw a clear line against the most extreme elements of the Islamist resistance, U.S. officials say.
But U.S. arms supplies for opposition fighters remain off the table for now - reflecting continued U.S. reluctance to intervene directly in the conflict even as allies such as Qatar and Saudi Arabia step up their own weapons shipments.
The U.S. scramble on Syria comes as rebels, who already control swaths of the country, intensify their push on Damascus, closing the highway to the capital's airport and battling government troops in the suburbs of what increasingly is a city under siege.
The rebel campaign has coincided with a series of warnings from world leaders to Assad not to use chemical weapons - a step U.S. President Barack Obama said would be a "tragic mistake" that would invite unspecified consequences.
U.S. Defense Secretary Leon Panetta on Thursday repeated those warnings and said the United States had reason to believe Damascus was contemplating chemical warfare. Syria has rejected the warnings as "a pretext for intervention" by outsiders.
"The intelligence that we have raises serious concerns that this is being considered," Panetta said.
NATO also decided this week to send U.S., German and Dutch batteries of Patriot anti-aircraft missiles to Turkey's border with Syria, meaning hundreds of American and European troops will deploy to the frontier for the first time.
But U.S. officials caution that Washington still sees no military solution to the conflict in Syria, a country crosscut by religious and sectarian divisions. Mapping out a durable political transition, they say, is the only way to avert a potentially larger catastrophe in the heart of the Middle East.
"The goal is not to push Assad out, the goal is to get a different kind of government in Syria, one that promotes stability and security. The fall of Bashar is just Act One," said Jon Alterman, director of the Middle East program at the Center for Strategic and International Studies in Washington.
Clinton met Foreign Sergei Lavrov of Russia in Dublin on Thursday, raising hopes that Moscow might reconsider its support for Assad, which has seen Russia, joined by China, veto three U.N. Security Council resolutions aimed at pressuring his government to halt the violence.
International mediator Lakhdar Brahimi, also at the meeting, emerged saying they had agreed to seek a "creative" solution to the Syrian crisis. But he gave no specific indications that the diplomatic deadlock had been broken.
The Marrakesh "Friends of Syria" meeting follows intense U.S. efforts to professionalize Syria's opposition after Clinton in October called for a new structure to replace the Syrian National Council, a group of largely expatriate Syrians with little political traction inside the country.
The new coalition was formed, and U.S. officials have met with some of its members, particularly on economic and humanitarian issues as they try to improve governance and service delivery in areas of Syria already under rebel control.
"At some point, it becomes more important whether they can pick up the garbage than whether they can shoot down a helicopter," said Daniel Serwer, a professor of conflict management at Johns Hopkins University.
Britain, France, Turkey and the Gulf countries have already endorsed the coalition despite having sometimes different ideas about what a post-Assad Syria should look like.
Qatar in particular, along with being an important weapons supplier for rebel forces, is seen to be pushing for a stronger Islamist political role in the country - a challenge to U.S. officials who hope to craft a more inclusive governing structure.
A U.S. move to upgrade its recognition of the coalition may strengthen its leverage but is unlikely to resolve deeper questions over whether the nascent opposition is really ready to take the reins in Syria.
Additional reporting by David Alexander and Tabassum Zakaria Editing by Warren Strobel and Eric Beech