The Feb. 21 front-page article “For Turkey, high stakes as troubles intensify” highlighted a critical development: The growing military alliance between Russia and Armenia is threatening Turkey, an indispensable U.S. ally and partner in the fight against the Islamic State.

The announcement that Russia is sending a new set of fighter jets and combat helicopters to an air base only 25 miles from the Turkish border is just the latest example of this alliance.

The two countries’ economic and military ties run deep, bolstered by economic and security agreements and two military bases — including one just outside the Armenian capital. Most significant, Armenia is the only country in the region that shares a border with Turkey and has Russian troops permanently stationed.

Although Armenia has welcomed thousands of Russian troops and advanced weaponry, these developments seemed to have escaped the notice of U.S. officials, who were settling in for the holidays while Russia and Armenia signed a sweeping air defense agreement two days before Christmas.

It’s time for Washington to assess who our real allies in the region are.

Andrew Bowen, Washington

The writer is senior fellow at the Center for the National Interest.