Even as Pentagon officials strive to wean themselves off using Russian booster engines to launch U.S. military satellites, they are studying a possible shift to European-built rockets.

Claire Leon, the Air Force’s top rocket-acquisition official, raised the matter during a space conference earlier this week, disclosing that the military has launched a study evaluating “whether it would be possible” to use rockets from Arianespace, Europe’s primary launch provider, to blast some U.S. national-security payloads into orbit.

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