Nanri island: 11 – 15 April 1952 Dongshan Island Campaign: 15 July 1953 First Taiwan Strait Crisis: August 1954 – May 1955 Battle of Yijiangshan: 18 January 1955 Tachen Evacuation: 7–11 February 1955 Second Taiwan Strait Crisis (August 23 Artillery Battle): 23 August – early October 1958 Second Battle of Dadan island: 26 August 1958 Vietnam War: 1960s, Deployment of small groups of ROC troops disguised as locals, transportation, and technical assistance. Not widely publicized to avoid PRC involvement. Battle of Dong-Yin: 1 May 1965 Battle of Wuchow: 13–14 November 1965 Yemen Civil War: 1979 to 1985: 80+ F-5E pilots plus ground crew sent to North Yemen to boost its air defense at the request of Saudi Arabia and the United States. At least one squadron strength was kept throughout the period, flying North Yemen's F-5E fleet. Third Taiwan Strait Crisis: 21 July 1995 – 23 March 1996 Southeast Asian tsunami relief: January 2005 Military intervention against ISIL: 13 June 2014 – present (Under CJTF-OIR) Nuclear weapons program The development of nuclear weapons by the ROC has been a contentious issue. The U.S., hoping to avoid escalating tensions in the Taiwan Strait, has continually opposed arming the ROC with nuclear weapons. Accordingly, the ROC, although not a member of the United Nations, adheres to the principles of the nuclear Non-Proliferation Treaty and has stated that it does not intend to produce nuclear weapons. Past nuclear research by the ROC makes it a 'threshold' nuclear state. In 1967, a nuclear weapons program began under the auspices of the Institute of Nuclear Energy Research (INER) at the Chungshan Institute of Science and Technology. The ROC was able to acquire nuclear technology from abroad (including a research reactor from Canada and low-grade plutonium from the United States) allegedly for a civilian energy system, but in actuality to develop fuel for nuclear weapons. After the International Atomic Energy Agency found evidence of the ROC's efforts to produce weapons-grade plutonium, Taipei agreed in September 1976 under U.S. pressure to dismantle its nuclear weapons program. The nuclear reactor was soon shut down and the plutonium mostly returned to the U.S. Another secret program was revealed after 1987 Lieyu massacre, when Colonel Chang Hsien-yi, deputy director of Nuclear Research at INER who was secretly working for the CIA, defected to the U.S. in December, and produced a cache of incriminating documents. In 1988 upon being questioned by