WASHINGTON, DC — U.S. President Donald Trump’s administration finds the expanding cooperation in Syria between U.S. NATO ally Turkey and Russia “gravely concerning,” a top Department of State (DOS) warned lawmakers.

On Wednesday, David Satterfield, the acting assistant secretary for the Bureau of Near Eastern Affairs at DOS, testified during a House Foreign Affairs Committee hearing alongside A. Wess Mitchell, the assistant secretary for DOS’ Bureau of European and Eurasian Affairs.

Despite being on opposite sides of the Syrian civil war, Russia, Turkey, and Iran have held various fruitless discussions to end the conflict, which has been raging since March 2011.

The talks have notably excluded the United States, which has deployed about 2,000 troops to primarily combat the Islamic State (ISIS/ISIL) in Syria.

In recent weeks, the Trump administration has been hinting at a possible U.S. withdrawal from Syria, pushing for regional ownership of the conflict to in lieu of the United States military presence.

Throughout the war, Russia and Iran have been supporting Assad while Turkey and to a lesser extent the United States have been backing opposition fighters.

Nevertheless, Mitchell noted in written testimony:

Turkey lately has increased its engagement with Russia and Iran. Ankara has sought to assure us that it sees this cooperation as a necessary stepping-stone towards progress in the Geneva [Syrian peace] process and as a means of de-escalating the conflict.

But the ease with which Turkey brokered arrangements with the Russian military to facilitate the launch of its Operation Olive Branch [against U.S.-allied Kurdish fighters] in [Syria’s] Afrin District—arrangements to which America was not privy—is gravely concerning.

It is in the American national interest to see Turkey remain strategically and politically aligned with the West, and we believe it is also in Turkey’s interests.

As an ally of Kurdish troops considered to be terrorists by Ankara, the United States finds itself in a stand-off against its NATO partner Turkey, which has decided to expand its Operation Olive Branch into northern Syria’s Manbij region.

U.S.-backed Kurdish troops control vast swathes of northern Syria, including Manbij.

Although U.S.-led coalition troops and their local allies have liberated “approximately 98 percent” of the territory once controlled by ISIS in its “crumbling” so-called caliphate in Iraq and Syria, problems remain, Satterfield declared in his written testimony, adding:

We recognize current challenges, such as in Manbij, Syria, where U.S. forces are located. We have made it very clear to the Turkish government that we will continue to operate there and are working hard with our NATO ally to find a roadmap to a resolution.

Mitchell acknowledged that the U.S. military is engaged in discussions with both Russia and Turkey to avoid clashes in Syria, telling lawmakers:

[Regargding Turkey], our policy has been to combine close engagement with clear messaging that the United States will actively defend its interests.

In the context of Syria, we have engaged in high-level interagency discussions, both to address legitimate Turkish security concerns and to avoid inadvertent collisions between our forces. These conversations are ongoing.

Stressing Moscow’s “intolerable” support for Assad, the State officials emphasized that U.S. and Russia have drastically different goals in Syria.

The Assad regime was on the brink of defeat before receiving assistance from Iran and Russia, but now the dictator controls more territory than any other warring party, including those backed by Turkey and the United States, respectively.

Referring to Russia, Mitchell testified:

Its reckless intervention in Syria and support for the Assad regime has raised the risk of confrontation with the West … America has done its part to avoid these [escalating] spirals.

We have brokered and maintain de-confliction [communication] channels to avoid collisions in an increasingly congested and complex battlespace … We do not seek a confrontation. But our forces will not hesitate to use necessary and proportionate force to defend themselves…

Russia’s primary goal in Syria is to maintain an ever-present military footprint in the Middle East as a means to expand its influence in the region, Mitchell said.

“It also wants to inflict a globally visible defeat on the United States … Moscow is willing to accept and impose catastrophic human costs to achieve these goals,” he added.