Final answer:
Oleg Penkovsky was a Soviet military intelligence officer who provided crucial information to the United States and the United Kingdom during the Cold War, but he was eventually discovered by the Soviet authorities and executed.
Step-by-step explanation:
Oleg Penkovsky was not a senior Soviet military intelligence officer, and he was not convicted of spying for the United Kingdom and the United States. Oleg Penkovsky was a Soviet military intelligence officer who provided crucial information to the United States and the United Kingdom during the Cold War. He worked as a double agent, providing highly valuable intelligence on the Soviet Union's military capabilities and nuclear program. His actions were instrumental in preventing a nuclear conflict between the superpowers. However, he was eventually discovered by the Soviet authorities, arrested, and executed in 1963.