Reagan himself made the major policy decisions, and often overruled his top advisers in cases such as the Reykjavík Summit in 1986, and his 1987 speech calling for tearing down the Berlin wall. He was concerned with very broad issues, as well as anecdotal evidence to support his beliefs. He paid very little attention to details and elaborate briefings. When senior officials did not work out, such as Secretary of State Alexander Haig, they were fired. Reagan went through a series of six national security advisers before settling on people he trusted. Indeed, the one of them John Poindexter was trusted too much. Poindexter and his aide Oliver North engaged in a secret deal with Iran called the Iran–Contra affair that seriously damaged Reagan's reputation. Reagan had rarely travelled abroad, and relied on an inner circle of advisers who were not foreign policy experts, including his wife, James Baker, Edwin Meese and Michael Deaver. Haig had the credentials to be Secretary of State, but he was arrogant and unable to get along with the other top aides. He was replaced by George P. Shultz, who proved much more collaborative, and has been generally admired by historians. Other key players included William J. Casey, director of the CIA, William P. Clark, national security advisor, and Jeane Kirkpatrick, Ambassador to the United Nations. Casper W. Weinberger, Secretary of Defense, successfully rebuilt and expanded the military, but did not coordinate well with the foreign policy leadership.