It has been suggested that Nixon was initially preoccupied with pursuing his policy of détente with the Soviet Union and with the May 1972 Moscow Summit, but later sought to assuage the Shah's concerns about Iraq during his May 30–31 trip to Tehran. In a May 31 meeting with the Shah, Nixon vowed that the U.S. "would not let down [its] friends," promising to provide Iran with sophisticated weapons ("including F-14s and F-15s") to counter the Soviet Union's agreement to sell Iraq Mig-23 jets.