https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-15#Design_and_development

In 1946 Soviet engine technology was far behind the West’s.[5] The Germans had been unable to develop airworthy turbojets with thrust over 1,130 kilograms-force (11,100 N; 2,500 lbf) capable of running for more than a few hours at the time of the surrender in May 1945, which limited the performance of immediate Soviet postwar jet aircraft designs. The Soviet aviation minister Mikhail Khrunichev and aircraft designer A. S. Yakovlev suggested to Premier Joseph Stalin that the USSR buy the reliable, fully developed, Rolls-Royce Nene (having been alerted to the fact that the UK Labour government wanted to improve post-war UK-Russia foreign relations) for the purpose of copying them in a minimum of time. Stalin is said to have replied, “What fool will sell us his secrets?"[6]

However, he gave his consent to the proposal and Mikoyan, engine designer Vladimir Yakovlevich Klimov, and others travelled to the United Kingdom to request the engines. To Stalin’s amazement, the British Labour government and its Minister of Trade, Sir Stafford Cripps, were perfectly willing to provide technical information and a license to manufacture the Rolls-Royce Nene. Sample engines were purchased and delivered with blueprints. Following evaluation and adaptation to Russian conditions, the windfall technology was tooled for mass-production as the Klimov RD-45 to be incorporated into the MiG-15.[7][5]