Complex sentence: In June 1961 Japan-US joint use agreement was established at Johnson, and active USAF use of the air base ended in June 1962 when the 41st Air Division headquarters moved to Yokota AB.
Split into simpler sentences: In June 1961 Japan-US joint use agreement was established at Johnson. The USAF ended its use of the air base in June 1962 when the 41st Air Division headquarters moved to Yokota AB.