A strike is called by the National Union of Seamen in the United Kingdom. In New York City, Dr. Martin Luther King Jr. makes his first public speech on the Vietnam War. May 19 – Gertrude Baniszewski is found guilty of torturing and murdering 16-year-old Sylvia Likens at a court in Indianapolis, United States, and is sentenced to life in prison (she is released on parole in December 1985). May 24 Battle of Mengo Hill: Ugandan army troops arrest Mutesa II of Buganda and occupy his palace. The Nigerian government forbids all political activity in the country until January 17, 1969. May 25 Explorer program: Satellite Explorer 32 (Atmosphere Explorer-B) is launched from the United States. No. 9 Squadron RAAF becomes part of the 4,500 strong Australian Task Force assigned to duties in Vietnam, leaving for Southeast Asia aboard the aircraft carrier HMAS Sydney. May 26 – British Guiana achieves independence, becoming Guyana. May 28 Fidel Castro declares martial law in Cuba because of a possible U.S. attack. The Indonesian and Malaysian governments declare that the Indonesia–Malaysia confrontation is over (a treaty is signed on August 11). Boat ride "It's a Small World" opens at Disneyland. May 29 – Sports stadium Estadio Azteca officially opens in Mexico City in advance of the 1968 Summer Olympics. May 31 – The Philippines reestablishes diplomatic relations with Malaysia. June June 2 Éamon de Valera is re-elected as Irish president. Surveyor program: Surveyor 1 lands in Oceanus Procellarum on the Moon, becoming the first U.S. spacecraft to soft-land on another world. Four former cabinet ministers including Évariste Kimba are executed in the Democratic Republic of the Congo, for alleged involvement in a plot to kill Mobutu Sese Seko. June 3 – Joaquín Balaguer is elected president of the Dominican Republic. June 5 – Gemini 9A: Gene Cernan completes the second U.S. spacewalk (2 hours, 7 minutes). June 6 – Civil rights activist James Meredith is shot by a sniper while traversing Mississippi in the March Against Fear. June 8 A North American XB-70 Valkyrie strategic bomber prototype is destroyed in a mid-air collision with an F-104 Starfighter chase plane during a photo shoot. NASA pilot Joseph A. Walker and USAF test pilot Carl Cross are both killed. 1966 Topeka tornado: Topeka, Kansas is devastated by a tornado that registers as an "F5" on the Fujita scale, the first to exceed US$100 million in damages.