In 1987, U.S. intelligence identified a missile battery for Chinese Silkworm (HY-2) anti-ship missiles roughly 36km south of the city of Kuhestak. [1] Iran deployed the missiles in reaction to Iraqi attacks on Iranian oil tankers in the 'tanker war' episode of the Iran-Iraq war. [2] According to historian Christopher Joyner, in 1988 Iran constructed an underground bunker at the site, designed to confound U.S. reconnaissance. [3]

Sources:
[1] "New Silkworm Missile Base Reported in Persian Gulf," Journal of Commerce, 2 June 1988, p.1B, www.journalofcommerce.com.
[2] Christopher C. Joyner, The Persian Gulf War: Lessons for Strategy, Law and Diplomacy (Santa Barbara, CA: Greenwood Press, 1990), p. 104.
[3] "Iran Said to Fortify Key Strait," The New York Times, 1 July 1988.