The United States has reportedly not enlisted the help of its Sea-Based X-Band Radar platform to prepare for a North Korean rocket launch planned for early April.

In a letter sent to U.S. Defense Secretary Robert Gates, Chairman of the Missile Defense Advocacy Alliance (MDAA) Riki Ellison pointed out that one of the U.S. military’s most valuable assets and its best tracking sensor for ballistic missile defense, the SBX, has not been deployed.

Elison’s letter comes after Gates’ recent remarks that Washington has no intent to intercept a North Korean missile.

The SBX, designed to detect incoming ICBMs to protect U.S. soil, was used in successful anti-missile defense tests conducted by the U.S. in December.