These concerns were a major factor in the unrequited efforts of both the Carter and Reagan administrations to improve relations with Iran, and resulted in massive aid to Pakistan's Muhammad Zia-ul-Haq. Zia's ties with the U.S. had been strained during Carter's presidency due to Pakistan's nuclear program and the execution of Zulfikar Ali Bhutto in April 1979, but Carter told Brzezinski and Secretary of State Cyrus Vance as early as January 1979 that it was vital to "repair our relationships with Pakistan" in light of the unrest in Iran.