That assessment comes despite public assertions by President Barack Obama and top aides that Putin has embarked on an ill-conceived mission in support of Syrian President Bashar al-Assad that it will struggle to afford and that will likely fail.
"I think it's indisputable that the Assad, with Russian military support, is probably in a safer position than it was," said a senior administration official, who requested anonymity. Five other US officials interviewed by Reuters on Monday concurred with the view that the Russian mission has been mostly successful so far and is facing relatively low costs.
The US officials stressed that Putin could face serious problems the longer his involvement in the more than four-year-old civil war drags on.
Yet since its campaign began on Sept. 30, Russia has suffered minimal casualties and, despite domestic fiscal woes, is handily covering the operation's cost, which analysts estimate at $1-2 billion a year. The war is being funded from Russia's regular annual defense budget of about $54 billion, a US intelligence official said.
The expense, analysts and officials said, is being kept in check by plummeting oil prices that, while hurting Russia's overall economy, has helped its defense budget stretch further by reducing the costs of fueling aircraft and ships. It has also been able to tap a stockpile of conventional bombs dating to the Soviet era.
Putin has said his intervention is aimed at stabilizing the Assad government and helping it fight the Islamic State in Iraq and the Levant group.
Prior to Russia's military action, US and Western officials claimed, Assad's government looked increasingly threatened.
Russia's intervention also appears to have strengthened its hand at the negotiating table. In recent weeks, Washington has engaged more closely with Russia in seeking a settlement to the war and backed off a demand for the immediate departure of Assad as part of any political transition.
Obama has suggested as recently as this month that Moscow is being sucked into a foreign venture that will drain its resources and bog down its military.
Russian casualties in Syria have been relatively minimal, officially put at three dead. US officials estimate that Russia may have suffered as many as 30 casualties overall.
Vasily Kashin, a Moscow-based analyst, said the war is not financially stressing Russia.
"All the available data shows us that the current level of military effort is completely insignificant for the Russian economy and Russian budget," said Kashin, of the Center for Analyses of Strategies and Technologies.
"It can be carried on at the same level year after year after year," he said.