(Adds quotes, details, background)
WASHINGTON, July 29 (Reuters) - If Russia's planned humanitarian operation for Aleppo is a ruse, it risks disrupting U.S.-Russian efforts to achieve a political solution to end the five-year Syrian civil war, the United States said on Friday.
Russia and Syrian President Bashar al-Assad's government on Thursday declared a "humanitarian operation" in the besieged rebel-held sector of Aleppo, opening "safe corridors" so people can flee Syria's most important opposition stronghold.
However, the United Nations has raised concerns about the plan and U.S. officials have suggested it may be an attempt to depopulate the city and to make fighters surrender. The opposition called it a euphemism for forced displacement.
"It has the risk, if it is a ruse, of completely breaking apart the level of cooperation," U.S. Secretary of State John Kerry said in response to a reporter's question as he began a meeting with the United Arab Emirates' foreign minister.
"On the other hand, if we're able to work it out today and have a complete understanding of what is happening and then agreement on the way forward, it could actually open up some possibilities," he added.
Asked if he thought the operation, which Russia's defense minister again described as "humanitarian" on Friday, was a ruse, Kerry said: "We are deeply concerned about the definition, and I have talked to Moscow twice in the last 24 hours."
"This is very much potentially a challenge, but we have a team that is meeting today working on this, and we'll find out whether or not it's real," he added. "We just don't know, fully, until we finish the conversations today."
Kerry did not say where the conversations were taking place, nor did he specify to whom he had spoken in Moscow. His usual Russian interlocutor is Foreign Minister Sergei Lavrov. (Reporting By Arshad Mohammed; Editing by Jonathan Oatis)
Our Standards: The Thomson Reuters Trust Principles.