paragraph_text: Rabah Bitat Airport , formerly known as Les Salines Airport, and popularly as El Mellah Airport is an international airport located south of Annaba, a city in Algeria. It is named after Rabah Bitat, a president of Algeria (1978-1979).

paragraph_text: Belo Horizonte - Tancredo Neves/Confins International Airport , formerly called Confins International Airport is the primary international airport serving Belo Horizonte. Since 2 September 1986 the airport is named after Tancredo de Almeida Neves (1910–1985), President-elect of Brazil. It is located in the municipality of Confins, in the Minas Gerais. It is operated by BH Airport S.A.

paragraph_text: Phoenix Sky Harbor International Airport (IATA: PHX, ICAO: KPHX, FAA LID: PHX) is a civil - military public airport 3 miles (2.6 nmi; 4.8 km) southeast of downtown Phoenix, in Maricopa County, Arizona, United States. It is Arizona's largest and busiest airport, and among the largest commercial airports in the United States.

paragraph_text: Louisville International Airport (IATA: SDF, ICAO: KSDF, FAA LID: SDF) is a public and military use public airport centrally located in the city of Louisville in Jefferson County, Kentucky, United States. The airport is situated on approximately 1,500 acres (6.1 km) and has three runways. Its IATA airport code, SDF, is based on the airport's former name, Standiford Field. Although it currently does not have regularly - scheduled international passenger flights, it is a port of entry, as it handles numerous international cargo flights.

paragraph_text: General Justo José de Urquiza Airport () is located on the southeast side of Paraná, a city in the Entre Ríos Province of Argentina. The airport covers an area of and is operated by Aeropuertos Argentina 2000. The airport is named for Justo José de Urquiza, president of the Argentine Confederation from 1854 to 1860.

paragraph_text: Maitland Airport, also known as Russell Field is a general aviation airport located in the suburb of Rutherford, approximately from Maitland in the Australian state of New South Wales. There are currently no airline services, with the airfield catering mostly to general aviation and recreational category aircraft. The airport has been owned and operated by the Royal Newcastle Aero Club since 1963 and shares a large training area with the nearby Cessnock Airport. Throughout its history, the airport has played host to many airshows, races and flying competitions. The field is named for the fifth President of the Royal Newcastle Aero Club, Robert Russell, who suffered a fatal heart attack while on the premises in 1966.

paragraph_text: The Alaska Purchase (Russian: Продажа Аляски, tr. Prodazha Alyaski) was the United States' acquisition of Alaska from the Russian Empire on March 30, 1867, by a treaty ratified by the United States Senate, and signed by president Andrew Johnson.

paragraph_text: The Eritrean Air Force (ERAF) is the official aerial warfare service branch of the Eritrean Defence Forces and is one of the three official uniformed military branches of the State of Eritrea.

paragraph_text: Bahías de Huatulco International Airport () is an international airport located at Huatulco, in the state of Oaxaca on Mexico. The airport handles national and international air traffic for the southern and southeastern Pacific coast of Oaxaca state.

paragraph_text: The Boeing C - 32 is a military passenger transportation version of the Boeing 757 for the United States Air Force. The C - 32 provides transportation for United States leaders to locations around the world. The primary users are the Vice President of the United States, using the distinctive call sign ``Air Force Two '', the First Lady and the Secretary of State. On rare occasions, other members of the U.S. Cabinet and Congressional leaders have been authorized to fly aboard the C - 32 for various missions. The C - 32, since its debut, has also served as Air Force One in place of the larger VC - 25A to airports that can not support the Boeing 747 - based jumbo jet.

paragraph_text: Smolensk North Airport (Russian военный аэродром "Смоленск-Северный", "Smolensk North Military Aerodrome") is a decommissioned military airbase in Smolensk Oblast, Russia, located 4 km north of the city of Smolensk. It is now used as Smolensk's sole airport for civil and military flights. It has a remote revetment area with 8 pads and a Yakovlev factory at the southeast side of the airfield, the Smolensk Aviation Plant.

paragraph_text: Platinum Airport is a state-owned public-use airport located in Platinum, in the Bethel Census Area of the U.S. state of Alaska.

paragraph_text: Jiayuguan Airport is an airport in Jiayuguan City, Gansu Province, China. It is located 9 kilometers northeast of Jiayuguan and also close to the city of Jiuquan. First built in 1938 for military use, the airport was rebuilt at the current location in 1953 and was formerly called Jiuquan Airport. It was expanded and reopened in August 2006.

paragraph_text: Lafayette Curry Baker (October 13, 1826 – July 3, 1868) was a United States investigator and spy, serving the Union Army, during the American Civil War and under Presidents Abraham Lincoln and Andrew Johnson.

paragraph_text: The Vice President of the United States (informally referred to as VPOTUS, or Veep) is a constitutional officer in the legislative branch of the federal government of the United States as the President of the Senate under Article I, Section 3, Clause 4, of the United States Constitution, as well as the second highest executive branch officer, after the President of the United States. In accordance with the 25th Amendment, he is the highest - ranking official in the presidential line of succession, and is a statutory member of the National Security Council under the National Security Act of 1947.

paragraph_text: Orlando International Airport (IATA: MCO, ICAO: KMCO, FAA LID: MCO) is a major public airport located six miles (10 km) southeast of Downtown Orlando, Florida, United States. In 2017, MCO handled 44,611,265 passengers, making it the busiest airport in the state of Florida and the eleventh - busiest airport in the United States.

paragraph_text: Schaumburg Regional Airport is a public use airport located northwest of Chicago, in the village of Schaumburg, in Cook and DuPage counties, Illinois, United States. The airport is owned by the Village of Schaumburg.

paragraph_text: Murtala Muhammed International Airport (MMIA) (IATA: LOS, ICAO: DNMM) is an international airport located in Ikeja, Lagos State, Nigeria, and is the major airport serving the entire state. The airport was initially built during World War II and is named after Murtala Muhammed, the 4th military ruler of Nigeria.

paragraph_text: The Chairman of the Joint Chiefs of Staff is, by law, the highest - ranking military officer of the United States Armed Forces, and the principal military adviser to the President of the United States. He leads the meetings and coordinates the efforts of the Joint Chiefs of Staff, comprising the chairman, the Vice Chairman of the Joint Chiefs of Staff, the Chief of Staff of the United States Army, the Commandant of the United States Marine Corps, the Chief of Naval Operations, the Chief of Staff of the United States Air Force, and the Chief of the National Guard Bureau. The Joint Chiefs of Staff have offices in The Pentagon. The chairman outranks all respective heads of each service branch, but does not have command authority over them, their service branches or the Unified Combatant Commands. All combatant commanders receive operational orders directly from the Secretary of Defense.

paragraph_text: Malta International Airport (Maltese: Ajruport Internazzjonali ta 'Malta, IATA: MLA, ICAO: LMML) is the only airport in Malta and it serves the whole of the Maltese Islands. It is located on island of Malta, between Luqa and Gudja, and occupies the location of the former RAF Luqa. It was completely refurbished, becoming fully operational on 25 March 1992. It is still referred to by locals as Luqa Airport, and sometimes as Valletta Airport internationally, as it is located 5 km (3.1 mi) southwest of the Maltese capital Valletta. The airport serves as the main hub for Air Malta and a base for Ryanair. It is also home to the Area Control Center and hosts the annual Malta Airshow, visited by military and civil aircraft from various countries. The airport is operated by Malta International Airport plc.

Question: In which military branch did the president during the purchase of the state where Platinum Airport is located serve?
Answer: Union Army