The American commander of the U.S.-led coalition against the Islamic State (ISIS/ISIL) in Iraq and Syria told reporters that losing the ancient Syrian city of Palmyra to the terrorist group “is probably an embarrassment” to the Russians, and it is up to them to take it back, noting that the city is “theirs” to defend.

“We’re just kind of staying out of it and watching it right now and protecting our own interest and letting the Russians sort that out, which I think is probably the common sense way to go about Palmyra,” U.S. Army Lt. Gen. Stephen Townsend, the commander, told Pentagon reporters via a video briefing from Baghdad on Wednesday, later adding, “The reason we’re not acting more aggressively [against ISIS in Palmyra] is first of all, that’s the first fact of life is that [Palmyra] was theirs [Russia’s].”

However, he added that the U.S.-led coalition may target weapons seized by ISIS when it captured the Syrian city if Russia fails to act, adding the equipment posed a threat to American forces and their allies in the region.

The general noted that he believes ISIS captured some armored vehicles, various guns, and other heavy weapons, adding that they may have taken air defense equipment.

“I anticipate that we’ll have opportunities to strike that equipment and kill the ISIL that’s operating it soon,” declared Townsend.

“I think maybe… we will strike it if we see it moving away from Palmyra,” he explained, later adding, “As long as it stays in Palmyra, the Russians will have lead [sic] and the regime will have the lead to deal with that.”

Russia and Iran-allied forces have been fighting opposition forces on behalf of Syrian dictator Bashar al-Assad. Syrian regime forces had been near collapse when Russia decided to join the fray, ultimately propping up Assad with the help of state-sponsor of terrorism Iran.

“Palmyra is their part of the [Russian] battle space, but because ISIL may have come into the possession of some significant pieces of weaponry there, we’re concerned about it,” said Gen. Townsend on Wednesday. “And I think Russia will probably take action. If they don’t, we will do what we need to do to defend ourselves and we’ll coordinate — we’ll de-conflict those actions with the Russians.”

The top U.S. general later backtracked his comments about Palmyra being part of the Syrian “battle space” belonging to Russia.

He explained:

There’s not necessarily a battle space, we don’t have an agreement with a map, with a boundary, the Russians have this and the coalition has that… There are facts of life, there are places where the [Syrian] regime are and there are places where the Russians are with the regime, usually, and there are places where the coalition and our partners are…

So at Palmyra, its not Russian battle space, I think I use that phrase kind of fairly loosely. But they were there, it was theirs, they were there with their Syrian proxies. So yes, they lost it and… I think it’s up to them probably to take it back.

He pointed out that Russia and the Assad regime are likely better positioned to have a sense of who is on the ground in Palmyra and adequately deal with the situation.

“We’re not sure who is there on the ground, 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,” noted Townsend.

The Kremlin claims the primary purpose of its intervention, which began in September 2015, is to combat ISIS.

However, U.S. officials and other analysts have accused Russia of not targeting ISIS and primarily focusing on other members of the Syrian opposition and killing civilians.

Earlier this year, Russian-backed Assad forces seized back Palmyra from ISIS, which conquered the area last year, but they recently lost the ancient city again to the jihadist group.

“I think they [Russia-Syria] failed to consolidate their gains and they got distracted by the things they were doing, took their eye off the ball there, the enemy sensed weakness and struck and gained a victory that I think will probably be fleeting,” said Gen. Townsend.

“I think this is probably an embarrassment to them [Russia-Syria] and I think they’ll devote adequate attention to holding the ground that they’re on,” he continued.

The recent fall of the northern Syrian city of Aleppo to Assad marks the biggest victory for the Syrian regime since the civil war started in March 2011.