The United States has deployed missile defense systems that will work with the Japanese and South Korean militaries to track a rocket that North Korea says it will launch some time over an 18-day period beginning on Monday, February 8, Reuters reports.

North Korea has notified UN agencies that it will launch a rocket carrying what it called an earth observation satellite some time between Feb. 8 and Feb. 25, triggering international opposition from some governments that see it as a long-range missile test.

North Korea says it has a sovereign right to pursue a space program. But it is barred under UN Security Council resolutions from using ballistic missile technology.

"We will, as we always do, watch carefully if there's a launch, track the launch, (and) have our missile defence assets positioned and ready," U.S. Defense Secretary Ashton Carter said on Thursday.

"We plan a lot about it. We and our close allies – the Japanese and the South Koreans - are ready for it."

South Korea has said its Aegis destroyers, its Green Pine anti-ballistic missile radar and early warning and control aircraft Peace Eye are ready.

A U.S. Navy spokesman confirmed the missile tracking ship USNS Howard O. Lorenzen arrived in Japan this week but declined to say if it was in response to the North's planned launch.