Question: Seattle–Tacoma International Airport and Sitka Rocky Gutierrez Airport, are in which country's initials?

Context paragraphs:
Rainier Beach station: Rainier Beach is a light rail station located in Seattle, Washington.  It is situated between the Tukwila International Boulevard and Othello stations on the Central Link line.  The line runs from Seattle–Tacoma International Airport to Downtown Seattle and the University of Washington as part of the Link light rail system.  The station consists of an at-grade island platform south of South Henderson Street in the median of Martin Luther King Jr.  Way in the Rainier Beach neighborhood, part of Seattle's Rainier Valley.

Sitka Rocky Gutierrez Airport: Sitka Rocky Gutierrez Airport (IATA: SIT, ICAO: PASI, FAA LID: SIT) is a state owned, public use airport located west of the central business district of Sitka, a city and borough in the U.S. state of Alaska that has no direct road access to the outside world, although it has car ferry access.

Scandinavian Airlines System Flight 933: Scandinavian Airlines System Flight 933 was a scheduled international flight from Denmark to the United States that on January 13, 1969, crashed into Santa Monica Bay at 19:21, approximately 6 nmi west of Los Angeles International Airport (LAX) in California, United States.  The crash into the sea was caused by pilot error during approach to runway 07R; the pilots were so occupied with the nose gear light not turning green that they lost their situation awareness and failed to keep track of their altitude.  The Scandinavian Airlines System (SAS) aircraft had a crew of nine with 36 passengers, of which 15 died.  The flight originated at Copenhagen Airport, Denmark, and had a stopover at Seattle–Tacoma International Airport, where there was a change of crew.

Washington State Route 509: State Route 509 (SR 509) is a 35.17 mi state highway in the U.S. state of Washington, connecting Tacoma in Pierce County to Seattle in King County.  The highway travels north from Interstate 705 (I-705) in Tacoma to SR 99 south of downtown Seattle.  It serves cities along the Puget Sound and west of Seattle–Tacoma International Airport in south King County, including Federal Way, Des Moines, and Burien.  SR 509 is part of the National Highway System and is a limited-access highway near the Port of Tacoma and from Burien to its northern terminus in Seattle.  Prior to the 1964 highway renumbering, the highway was part of Secondary State Highway 1V (SSH 1V) from Tacoma to Des Moines and SSH 1K from Des Moines to Seattle.  SR 509 was re-aligned onto the Burien Freeway in 1968 and the Port of Tacoma bypass in 1997, coinciding with the opening of its interchange with I-705 and the cable-stayed 21st Street Bridge.  Various proposals since 1988 have recommended building a freeway extension of SR 509 within the city of SeaTac, connecting the Burien Freeway to I-5, that remains unbuilt.

Sitka Seaplane Base: Sitka Seaplane Base (FAA LID: A29) is a public use seaplane base owned by and located in Sitka, a city and borough in the U.S. state of Alaska.  It is included in the National Plan of Integrated Airport Systems for 2011–2015, which categorized it as a "general aviation" facility.  This seaplane base is located near the Sitka Rocky Gutierrez Airport.

Downtown Seattle Transit Tunnel: The Downtown Seattle Transit Tunnel (DSTT), also referred to as the Metro Bus Tunnel, is a 1.3 mi pair of public transit tunnels in Seattle, Washington, United States.  The tunnel serves Downtown Seattle, running west under Pine Street from 9th Avenue to 3rd Avenue, and south under 3rd Avenue to South Jackson Street.  It was used only by buses from its opening in 1990 until 2005, and since 2009 it has been shared by buses and light rail.  The double-track tunnel and its stations, except Convention Place, constitute parts of the Central Link light rail line, which continues north to the University of Washington station and south through the Rainier Valley to Seattle–Tacoma International Airport as part of Sound Transit's Link light rail network.  Its five stations are also served by King County Metro and Sound Transit Express buses that leave the tunnel north via Interstate 5, south via the SODO Busway, or east via Interstate 90.  The DSTT is the busiest section of the Link light rail network, with an average of over 10,000 weekday boardings.  It is owned by King County Metro and shared with Sound Transit through a joint-operating agreement signed in 2002.  The Downtown Seattle Transit Tunnel is one of two tunnels in the United States shared by buses and trains, the other being the Mount Washington Transit Tunnel in Pittsburgh, and is the only one in the United States with shared stations.

Tukwila International Boulevard station: Tukwila International Boulevard is a light rail station located in Tukwila, Washington.  It is situated between the SeaTac/Airport and Rainier Beach stations on the Central Link line, which runs from Seattle–Tacoma International Airport to Downtown Seattle as part of the Link light rail system.  The station consists of two elevated side platforms enclosed in a structure northeast of the interchange of State Route 99 and State Route 518.  As one of two park and rides along the line, it also includes a total of 662 parking spaces in two nearby lots.

Seattle–Tacoma International Airport: Seattle–Tacoma International Airport (IATA: SEA, ICAO: KSEA, FAA LID: SEA) , also referred to as Sea–Tac Airport or Sea–Tac ( ), is the primary commercial airport serving the Seattle metropolitan area in the U.S. state of Washington.  It is located in the city of SeaTac, approximately 13 mi south of Downtown Seattle.  The airport, the largest in the Pacific Northwest region of North America, is owned and operated by the Port of Seattle.

Stadium station (Sound Transit): Stadium is a light rail station located in Seattle, Washington.  It is situated between the SODO and International District/Chinatown stations on the Central Link line, which runs from Seattle–Tacoma International Airport to Downtown Seattle and the University of Washington as part of the Link Light Rail system.  The station consists of an at-grade island platform at the intersection of the SODO Busway and South Royal Brougham Way in the SODO neighborhood of Seattle, adjacent to CenturyLink Field and Safeco Field.

Federal Detention Center, SeaTac: The Federal Detention Center, SeaTac (FDC SeaTac) is a prison operated by the Federal Bureau of Prisons.  It is located in SeaTac, Washington, near the Seattle–Tacoma International Airport, 12 mi south of downtown Seattle and 16 mi north of Tacoma, 1 mi west of the 200th Street exit at the Interstate 5.  The administrative facility employed 200 staff as of 2002 and housed 608 male and female inmates as of March 23, 2015.

Supporting paragraphs: Seattle–Tacoma International Airport Sitka Rocky Gutierrez Airport
Answer: U.S.