WASHINGTON — Russia asked on Monday to fly surveillance planes equipped with high-powered digital cameras over the United States, fueling a long-simmering debate among Pentagon and intelligence officials over Russia’s intentions to use such flights to spy on American power plants, communications networks and other critical infrastructure.

Russia has for years conducted unarmed observation flights over the United States — as the United States does over Russia — as part of the Open Skies Treaty, which was signed in 1992 by both nations and 32 other countries at the end of the Cold War, and entered into force a decade later. Although the treaty and the flights, unfamiliar to most Americans, amount to officially sanctioned spying, their goal has been to foster transparency about military activity and to reduce the risk of war and miscalculation, especially in Europe.

Now some senior American intelligence and military officials say the new digital technology, combined with shifting Russian flight plans, will violate the spirit of the treaty. Some Republicans also expressed alarm.

“I cannot see why the United States would allow Russia to fly a surveillance plane with an advanced sensor over the United States to collect intelligence,” Representative Mac Thornberry, a Texas Republican who heads the House Armed Services Committee, said in a statement on Monday.