The Missile Defense Agency’s big Sea-Based X-Band Radar tracking ship sailed out of Pearl Harbor on Friday — about three weeks ahead of North Korea’s planned space launch.

Agency spokeswoman Pam Rogers said she couldn’t discuss the radar’s operations or whether it will be used to monitor the upcoming rocket test.

The towering radar tracker "is returning to sea to continue its mission as a part of the ballistic missile defense system," Rogers said Monday.

Where the radar will operate also is unclear, but it doesn’t have to be near the Korean peninsula to track the space launch. Agency officials in the past have said the radar could track a baseball-size object flying through space on the East Coast while the SBX was on the West Coast.

North Korea said last month it was suspending nuclear and long-range missile testing in exchange for food aid from the United States, then announced March 16 that it would send into space an Earth observation satellite to mark the 100th birthday of the late President Kim Il Sung.

The planned launch, which North Korea said will take place between April 12 and 16 on a long-range Unha-3 rocket, has been condemned by the United States as a ballistic missile test and destabilizing for the region.

In June 2009 then-Defense Secretary Robert Gates ordered the SBX missile tracker — which was in Pearl Harbor at the time — to sea as North Korea prepared a space launch with Hawaii in the flight path.

Gates said at the time that Hawaii had the Terminal High Altitude Area Defense system to guard against a North Korean missile.

For the upcoming launch, North Korea has said its rocket would travel south, with the first stage falling into the ocean off the west coast of South Korea and the second stage landing east of the northern Philippines.

The $1 billion SBX’s inflated dome has a phased array radar studded with 45,000 geometrically placed radiating elements, each about a foot long.

The SBX is the defense agency’s principal sensor for ballistic missile defense while a rocket is in the midcourse of flight outside Earth’s atmosphere, but can engage ballistic missile threats in all phases of flight, the agency said.

Rogers said the SBX will return to Pearl Harbor, but did not specify a date.