Question:  Montrose Regional Airport a public airport as opposed to Luis Muñoz Marín International Airport which is what?
Context: Fina Air was an airline based in San Juan, Puerto Rico named after Josefina Canto who was the mother of Lazaro Canto.  It operated charter flights to the Dominican Republic from Luis Muñoz Marín International Airport in San Juan, Rafael Hernández Airport in Aguadilla and Eugenio María de Hostos Airport in Mayagüez.  The airline has now ceased operations. Montrose Regional Airport (IATA: MTJ, ICAO: KMTJ, FAA LID: MTJ) is a non-towered public airport on the northwest side of Montrose, in zip code 81401 in southwestern Colorado.  Its two runways are at elevation 5,759 feet (1,755 m).  MTJ covers 966 acres (391 ha) of land. Luis Muñoz Marín International Airport (IATA: SJU, ICAO: TJSJ, FAA LID: SJU) (Spanish: "Aeropuerto Internacional Luis Muñoz Marín" , Or Isla Verde International Airport/Aeropuerto Internacional de Isla Verde) is a joint civil-military international airport named for Puerto Rico's first democratically elected governor and located in suburban Carolina, Puerto Rico, 3 mi southeast of San Juan.  It is the busiest airport in the Caribbean region by passenger traffic.  Over 4 million passengers board a plane at the airport per year according to the Federal Aviation Administration. Retrato de Luis Muñoz Marín (Portrait of Luis Muñoz Marín) is a 1977 oil painting by the Puerto Rican artist Francisco Rodón of the first democratically elected governor of Puerto Rico. Prinair Flight 191 was a Prinair (Puerto Rico International Airlines) flight from Luis Muñoz Marín International Airport in San Juan, Puerto Rico, to Mercedita Airport in Ponce, Puerto Rico.  At approximately 11:15pm on 24 June 1972, the aircraft crashed while attempting to land at Mercedita Airport.  Five people died in the accident.  and the remaining people were injured. Merlin Airways is an American airline based in Billings, Montana, USA.  It operates freight services under contract to FedEx Express and UPS Airlines.  The airline previously conducted FAR Part 121 passenger operations in Alaska and Texas as well as providing charter service for gambling junkets.  As of 1999 the company has ceased passenger operations to focus on the main aspect of their business which is providing freight services to FedEx and UPS.  Its headquarters is Billings, Montana, with hubs at Miami International Airport and at Luis Muñoz Marín International Airport, San Juan, Puerto Rico. Air Caribbean was an airline that served from Luis Muñoz Marín International Airport, then "Isla Verde International Airport", in San Juan.  The 1970s and 1980s were decades when several Puerto Rican airlines existed and competed against each other, including Prinair, Vieques Air Link and Dorado Wings.  Believing a share of the market profits could be gained, Air Caribbean was created in 1975. The Tito Puente Amphitheatre (or Anfiteatro Tito Puente in Spanish) is a concert amphitheater in San Juan, Puerto Rico.  It is named after the late mambo musician and percussionist Tito Puente.  It was previously named "Luis Muñoz Marín Amphitheatre" (or Anfiteatro Luis Muñoz Marín") Dorado Wings was a small commuter airline that operated from Luis Muñoz Marín International Airport in San Juan, Puerto Rico to Dorado Airport in the tourist center of Dorado.  Dorado Wings was the only commercial operator at Dorado Airport.  Dorado Wings existed from 1964 to 1982.  In early 1981, the airline was purchased and its name was changed to Crown Air which operated until 1988. Aerostar Airport Holdings, LLC is the public–private partnership, privately held company, and limited liability company that operates and manages the Luis Muñoz Marín International Airport on behalf of the Puerto Rico Ports Authority.  The company is an equitable joint venture between Highstar Capital, an infrastructure investment firm, and Grupo Aeroportuario del Sureste, a Mexican airport management firm.  Aerostar has a forty-year lease to manage and upgrade the airport, including the investment of nearly $1.4 billion in capital improvements over the course of the lease.
Answer: joint civil-military international airport