MOSCOW—Travel to and from Russia’s once-thriving airports is declining as fewer locals venture outside the country and foreign tourist and business visitors dry up.

Moscow’s three airports spent hundreds of millions of dollars on expansions in the past decade to keep up with airline demand for terminals and runways. But now, air traffic is declining as recession hits consumers and Russia’s isolation deepens.

During previous downturns in the Russian economy, and even during the 1998 financial collapse, international airlines “cut back the size of their planes, but they always kept the flights,” said Alexis Rodzianko, president of the American Chamber of Commerce in Russia and a longtime resident. “This is much more drastic than anything I’ve ever seen them do before.”

Delta Air Lines Inc., the only U.S. carrier to Russia, said last month that it would suspend its New York to Moscow service for the winter for the first time since the Cold War. Delta, which had already reduced its flights for spring and summer, said it was reducing capacity to international destinations where “demand has been negatively impacted by the decline in oil prices,” though Moscow was the only destination where flights will be suspended altogether.

EasyJet PLC, which trumpeted its success in accessing the lucrative market in 2012, reduced flights starting Jan. 26 and will almost halve the number by the summer, citing a lack of demand. Qatar Airways and Etihad Airways slashed flights to Moscow in recent months. Air India Ltd. said it would reduce trips from Delhi to Moscow to two a week, and Cathay Pacific Airways Ltd. said it would end service to Moscow in June. Austrian Airlines, a unit of Deutsche Lufthansa AG , and CSA Czech Airlines have cut flights to regional destinations within Russia.