Iklé's expertise was in defense and foreign policy, nuclear strategy, and the role of technology in the emerging international order.

After a career in academia (including a professorship at MIT) he was appointed director of the Arms Control and Disarmament Agency in 1973–1977, before becoming Under Secretary of Defense for Policy (1981 to 1988).

He successfully proposed and promoted the idea of supplying the rebels with anti-aircraft Stinger missiles, overcoming CIA opposition.

As an under secretary of defense, Iklé led the effort to lobby for National Security Decision Directive 166 ("Expanded US Aid to Afghan Guerrillas"), signed by Reagan in March 1985.

[11] "We began to understand that what to us was a very big deal back in Washington, from the point of view of the president, is a second order priority handled by one GS [civil service officer]," according to Michael Pillsbury, Iklé's deputy.

[12] CIA Deputy Director John McMahon, who resisted the proposal, was the target of a letter-writing campaign by conservative groups.

[15] In 1975 and 1987, Iklé received the highest civilian award of the Department of Defense, the Medal for Distinguished Public Service.

"[16] He was the author of several books and numerous articles on defense, foreign policy, and arms control, including How Nations Negotiate and Every War Must End.