Question: Who is the operator of a space-based radionavigation system which is the base of the QZSS?

Context paragraphs:
SLDCOM: SLDCOM is a satellite communications system operated by the U.S. National Reconnaissance Office and used by the United States armed forces.  The space-based assets of the system were flown as part of the Satellite Launch Dispenser (SLD) hardware on several Titan IV rocket launches which also launched Naval Ocean Surveillance System satellites.  The SLDCOM system provides bent pipe UHF communications.

GLONASS: GLONASS (Russian: ГЛОНАСС , ] ; Глобальная навигационная спутниковая система ; transliteration "Globalnaya navigatsionnaya sputnikovaya sistema "), or "Global Navigation Satellite System", is a space-based satellite navigation system operating in the radionavigation-satellite service.  It provides an alternative to GPS and is the second navigational system in operation with global coverage and of comparable precision.

Global Positioning System: The Global Positioning System (GPS), originally Navstar GPS, is a space-based radionavigation system owned by the United States government and operated by the United States Air Force.  It is a global navigation satellite system that provides geolocation and time information to a GPS receiver anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites.

2d Space Warning Squadron: The 2d Space Warning Squadron (2SWS) Is part of the 460th Space Wing at Buckley Air Force Base, Colorado.  It operates the Space-Based Infrared System (SBIRS) satellites conducting global monitoring for significant infrared events.

Theater Event System: The United States Theater Event System (TES) is a missile-warning system.  The TES is composed of three ground elements: the Space-Based Infrared System (SBIRS) Mission Control Station, the JTAGS, and the Tactical Detection and Reporting system.  The TES in-theater capability will be enhanced significantly as its hardware and software are upgraded to interface with the future SBIRS High and Space Tracking and Surveillance System satellite constellations.

Quasi-Zenith Satellite System: The Quasi-Zenith Satellite System (QZSS) is a three-satellite regional time transfer system in development and the satellite-based augmentation system for the Global Positioning System that would be receivable within Japan.  The first satellite "Michibiki" was launched on 11 September 2010.  Full operational status was expected by 2013.  In March 2013, Japan's Cabinet Office announced the expansion of the Quasi-Zenith Satellite System from three satellites to four.  The $526 million contract with Mitsubishi Electric for the construction of three satellites is slated for launch before the end of 2017.  The basic four-satellite system is planned to be operational in 2018.

Tselina (satellite): Tselina (rus. " Целина") is a Russian, formerly Soviet, military space-based radio surveillance system.  It is capable of determining the exact location of radio-emitting objects and also their type, modes of operation, and how active they are.  For instance, preparation for a military operation may raise the activity of the radio communications.  Detection of these communications by a space-based surveillance system can provide early warning of this activity, warning that may be unavailable by other means.

USA-205: USA-205, also known as Space Tracking and Surveillance System Advanced Technology Risk Reduction (STSS-ATRR), and previously as Block 2010 Spacecraft Risk Reduction is a satellite formerly operated by the United States Missile Defense Agency.  It was launched to demonstrate new technology for missile detection early warning systems.  The technology demonstrated on STSS-ATRR will be used in the development of the Space Tracking and Surveillance System part of the Space-Based Infrared System.

Missile Warning Center: The USSTRATCOM Missile Warning Center (MWC) is a Cheyenne Mountain nuclear bunker facility which networks data from missile warning sensor systems including the "space-based infrared system" and the terrestrial radars of the Solid State Phased Array Radar System.  The United States Strategic Command center is a $2.9 billion facility completed in 2011 and operated under the Joint Functional Component Command for Space.  The MWC disseminates data over the Integrated Broadcast Service (e.g., theater event exercise reports) and the Shared Event Warning (SEW) system, e.g., messages and voice warning to partner countries.  MWC security and support is provided by the Air Force Space Command's 721st Mission Support Group.

Visual binary: A visual binary is a gravitationally bound system that can be resolved into two stars.  These stars are estimated, via Kepler's 3rd law, to have periods ranging from a number of years to thousands of years.  A visual binary consists of two stars, usually of a different brightness.  Because of this, the brighter star is called the primary and the fainter one is called the companion.  If the primary is too bright, relative to the companion, this can cause a glare making it difficult to resolve the two components.  However, it is possible to resolve the system if observations of the brighter star show it to wobble about a centre of mass.  In general, a visual binary can be resolved into two stars with a telescope if their centres are separated by a value greater than or equal to one arcsecond, but with modern professional telescopes, interferometry, or space-based equipment, stars can be resolved at closer distances.

Supporting paragraphs: Quasi-Zenith Satellite System Global Positioning System
Answer: United States Air Force