The United States must contend with growing competition from Russia and China across the Middle East following the defeat of the Islamic State, a senior U.S. official told lawmakers Tuesday.

Gen. Joseph Votel, head of U.S. Central Command (Centcom), described an array of steps those “great power” nations have taken to expand their military and political clout in a way that challenges American interests from Syria to Afghanistan.

Describing the chief issues facing the U.S. military in the region, Votel took aim at what he characterized as Moscow’s attempts to monopolize events in Syria, where the course of a grinding civil conflict was redirected by Russia’s military intervention in 2015.

Although President Vladimir Putin announced a drawdown of Russian forces from Syria in December, Moscow’s continued military support for Syrian President Bashar al-Assad has allowed his government to claw back areas under opposition control.

In Syria, “Moscow is playing the role of arsonist and firefighter . . . fueling tensions and then trying to resolve them in their favor, and then manipulating all the parties they can in order to achieve their objectives,” he said during testimony before the House Armed Services Committee.

The new focus reflects a shift outlined in the Trump administration’s recent national defense strategy, which seeks to reorient the Pentagon from the counterinsurgency wars that followed the Sept. 11, 2001, attacks toward competition with large, sophisticated nations posing a threat to U.S. military primacy.

Although U.S. officials acknowledge that counterterrorism threats emanating from the Centcom region are far from being vanquished, they also have embraced a “great powers” lens to view the region.

Syria in particular, Votel said in his written statement, has emerged as a testing ground for new Russian weapons and military tactics, often without taking care to protect civilians. Enhanced Russian air defenses likewise pose a new threat to U.S. air activities in the region.

The general said that Russia was seeking to exploit differences among the complicated array of factions in Syria — the Assad government, Iran and Turkey, along with the United States and the Kurdish forces it has supported against the Islamic State.

While the United States and its allies have pushed the Islamic State out of most areas it once controlled, a U.S. force of about 2,000 troops remains in northern and eastern Syria in a bid to prevent the extremists from returning.

The general blamed Russia for failing to enforce a U.N.-backed cease fire approved over the weekend. “Either Russia has to admit that it’s not capable, or it doesn’t want to play a role in ending the Syrian conflict here,” he said. “I think their role is incredibly destabilizing.”

Votel, meanwhile, said that Russia had “exaggerated” the threat posed by an Islamic State affiliate in Afghanistan and had mischaracterized that group’s rise as an indication of a failed U.S. strategy.

Votel also referred toChina’s growing military ambitions in the region, citing a new base in Djibouti, its attempts to expand arms sales to U.S. allies and, like Russia, its efforts to develop “multidimensional” ties with U.S. adversary Iran.

The general suggested that the United States would try to balance the new focus on great- power competition and the ongoing threats from militant groups by relying on allies in a way that might allow for a smaller U.S. footprint in the region.

U.S. efforts to elevate the military capabilities of regional allies have had mixed success.

One large-scale threat identified by the Trump administration that does reside within the Middle East is Iran. Officials have said that pushing back against Tehran’s support for armed proxy groups across the region, including in Syria and Yemen, and ensuring that Iran cannot obtain nuclear weapons are top priorities.