MOSCOW — These have been disastrous weeks for American foreign policy, a popular presenter on Russia’s state television told viewers on Sunday night with an I-told-you-so smirk.

The United States essentially turned its back on Ukraine amid the impeachment inquiry, the TV host Dmitri Kiselyov said in his marquee weekly show. Then, Washington abandoned the Syrian Kurds.

“The Kurds themselves again picked the wrong patron,” Mr. Kiselyov said. “The United States, of course, is an unreliable partner.”

As the Middle East reels from President Trump’s erratic foreign policy, Russia is savoring a fresh chance to build its status as a resurgent world power and cast itself as a force for stability. The withdrawal of United States troops from northeastern Syria, coupled with Turkey’s incursion, is allowing Russia to play the part of responsible peacemaker and to present a contrast to what many in the region see as unstable leadership from Washington.