The US Department of Commerce intensified its crackdown on Russian airlines on Thursday, hitting Aeroflot, Azur Air and UTair with enforcement measures for violating US export controls issued after the Russian invasion of Ukraine. The enforcement action denies the three Russian carriers export privileges and targets all airlines, not just specific aircraft. The US government believes that the actions over time will make air carriers largely unable to continue flying. The United States has previously identified more than 170 Boeing aircraft used by Russian airlines in violation of US sanctions, including about 40 Aeroflot Boeing 737 and 777 aircraft, 21 Boeing Azur aircraft and 17 UTair Boeing aircraft. Live Russia-Ukraine updates Export controls prevent companies around the world from supplying, maintaining, repairing or spare parts or services to recognized aircraft. Deputy Commerce Secretary Don Graves said the message was clear: “Defy our export controls at your own risk.” Assistant Secretary of Commerce for Export Enforcement Matthew Axelrod said the government believes that “Aeroflot, Azur Air and UTair and their fleet of aircraft over time will largely be unable to continue flying to either internationally or domestically, as they are now disconnected from international support and US Spare Parts and related services needed to maintain and support their fleets. The airlines did not immediately respond to a request for comment. “Our export controls are working,” Graves said, adding that U.S. exports to Russia of items subject to new licensing requirements have been reduced by 99 percent in value. The orders prohibit service for maintenance contracts and the use of any U.S. spare parts to service recognized aircraft, but the Department of Commerce could approve safety-critical components on a case-by-case basis. The Commerce Department said that after restricting the planes in March, Aeroflot continued to fly to Beijing, Delhi, Antalya and Istanbul, Dubai and some Russian domestic flights. Azur Air continued flights to Turkey, Dubai and Vietnam, as well as some domestic flights to Russia, while UTair flew to Tajikistan, Armenia, Azerbaijan, Saudi Arabia and Uzbekistan, as well as some domestic flights to Russia, the ministry said. Any aircraft of U.S. origin or foreign aircraft containing more than 25 percent controlled content of U.S. origin is subject to a license requirement if it is Russian-owned or operated and exported to Russia. The United States, the European Union and other countries have banned Russian aircraft from US airspace. Russia’s largest cargo airline, Volga-Dnepr Group, announced on March 18 that it had suspended all flights with Boeing aircraft due to Western sanctions. Volga-Dnepr announced that it had shut down two of its subsidiaries. AirBridgeCargo and Atran. S7, Russia’s largest private airline and the second largest overall, also said on March 4 that it was suspending all international flights. Be smart with your money. Receive the latest investment information delivered directly to your inbox three times a week with the Globe Investor newsletter. Register today.