Given the question: I want to test the ability of students to read a passage and answer questions about it. Could you please come up with a good question for the passage "Construction began in 1941 of two airbases consisting of 5.8 km2 (2.2 sq mi) of land, largely reclaimed from the sea. For many years, Bermuda's bases were used by US Air Force transport and refuelling aircraft and by US Navy aircraft patrolling the Atlantic for enemy submarines, first German and, later, Soviet. The principal installation, Kindley Air Force Base on the eastern coast, was transferred to the US Navy in 1970 and redesignated Naval Air Station Bermuda. As a naval air station, the base continued to host both transient and deployed USN and USAF aircraft, as well as transitioning or deployed Royal Air Force and Canadian Forces aircraft."?
The answer is:
Whose submarines, between the Germans and Soviets, were the Bermuda bases first used to look out for?