By Phil Stewart and David Alexander

WASHINGTON (Reuters) – The head of U.S. forces fighting Islamic State said on Wednesday the United States may target weapons seized by the group when it captured the Syrian city of Palmyra, adding the equipment posed a danger to the U.S.-led coalition in the region.

Army Lieutenant General Stephen Townsend told a Pentagon video briefing that the weapons seized by Islamic State likely included armored vehicles, guns and possibly air defense equipment or other heavy weaponry.

He hoped Russia or Syria would quickly retake Palmyra and neutralize the threat, but cautioned the United States would stand ready to strike if needed, including if the looted weapons started moving out of the city.

“Basically anything they seized poses a threat to the coalition but we can manage those threats and we will,” Townsend said. “I anticipate that we’ll have opportunities to strike that equipment and kill the ISIL that’s operating it soon.”

Still, he cautioned that Russia or Syria would have a far better sense of who was on the ground and would be in a better position to react quickly.

“We can’t tell one side from the other. So we can’t tell if the truck and the armored vehicle is being operated by a regime trooper, a Russian trooper or ISIL fighter,” he said, using an acronym for Islamic State.

Islamic State recaptured the ancient city of Palmyra on Sunday despite dozens of Russian air strikes to push back the militants, exposing the limitations of the Russian backing that has turned the tide of the conflict in Syrian President Bashar al-Assad’s favor.

The focus of Syria’s overstretched army on defeating insurgents in their last urban stronghold of Aleppo may have diverted resources needed to defend the city, where Moscow in recent months beefed up its defenses.

Palmyra, with its Roman-era city and spectacular ruins, had been recaptured from the militants last March, in what was hailed as a major victory for the government and the biggest reversal for Islamic State in Syria since Russia’s intervention.

‘FLEETING VICTORY’

“(They) took their eye off the ball there, the enemy sensed weakness and struck and gained a victory that I think will probably be fleeting,” Townsend said.

White House spokesman Josh Earnest said that if it were true the militants seized an anti-aircraft missile system, the threat from Islamic State “is worse because of the failed strategy of the Syrians and the Russians.”

By taking full control of Aleppo, Assad has proved the power of his military coalition and dealt a crushing blow to rebel hopes of ousting Assad after revolting against him during the 2011 Arab uprisings.

Rebels have been supported by the United States, Turkey and Gulf monarchies, but the support they have enjoyed has fallen far short of the direct military backing given to Assad by Russia and Iran.

Townsend said he expected rebels who lost Aleppo would take their fight elsewhere in Syria but that it was unlikely to significantly affect the U.S.-backed effort against Islamic State – including a bid to capture the group’s stronghold of Raqqa, Syria.

“Our estimate is they’ll probably go somewhere else that is more important to them, and I won’t care to comment on where we think that might be,” he said.

(Reporting by Phil Stewart and David Alexander; Editing by Peter Cooney)