WASHINGTON • Russia has sent a military advance team to Syria and is taking other steps that the United States fears may signal that Russian President Vladimir Putin is planning to vastly expand his military support for President Bashar al-Assad of Syria, administration officials said last Friday.
The Russian moves, including the recent transport of prefabricated housing units for hundreds of people to a Syrian airfield and the delivery of a portable air traffic control station there, are another complicating factor in US Secretary of State John Kerry's repeated efforts to enlist Mr Putin's support for a diplomatic solution to the bloody conflict in Syria.
The Russians have also filed military overflight requests with neighbouring countries for this month.
US officials acknowledge that they are not certain of Russia's intentions, but some say the temporary housing suggests that Russia could deploy as many as 1,000 advisers or other military personnel to the airfield near the Assad family's ancestral home.
The airfield serves Latakia, Syria's principal port city.
Other US officials say they see no indication that Russia intends to deploy significant numbers of ground forces, but they say the housing would enable Moscow to use the airfield as a major hub for ferrying in military supplies for the Syrian government or possibly as a launch pad for Russian airstrikes in support of Mr Assad's forces.
US intelligence analysts are also looking at ship loadings in Russia to determine what might be bound for Syria, and one official speculated that the Russian deployment might eventually grow to 2,000 to 3,000 personnel.
"There are some worrisome movements - logistical, preparatory types of things," said an administration official, who added that there was no confirmation that large numbers of Russian soldiers, aircraft or heavy weapons had yet arrived.
Syria is one of Russia's major arms clients and is also host to a Russian naval base at the port city Tartus.
Last Friday in Vladivostok, Russia, Mr Putin dismissed news reports that Russia had sent ground troops to fight in Syria as "premature". "We are looking at various options but, so far, what you are talking about is not on the agenda," he said at a news conference at the Eastern Economic Forum.
But Mr Putin said Russia was supplying arms to the Assad government under contracts that go back five to seven years and suggested that the Syrian authorities should be part of a new international alliance against terrorism.
Outlining his ideas on a potential diplomatic solution, Mr Putin suggested that it be carried out in parallel with the fight against extremists and that Mr Assad should play a role in the political process.
"The Syrian President, as a matter of fact, agrees with that, including holding early elections, parliamentary elections and establishing contact with the so-called 'healthy' opposition, bringing them into governing," Mr Putin said.
He did not elaborate on which opposition should be considered "healthy".
NEW YORK TIMES