The White House on Sunday defended the Republic of Korea's pursuit of longer-range missiles to cope with perceived threats from the Democratic People's Republic of Korea (DPRK).

"The ROK's new missile guidelines are designed to improve the Republic of Korea's ability to defend against DPRK ballistic missiles," White House spokesman Jay Carney told reporters aboard Air Force One en route to Los Angeles.

"The revisions are a prudent, proportional and specific response to the DPRK," he added.

The ROK is now allowed to develop ballistic missiles with a range of up to 800 kilometers, more than double the current limit, under a revised pact with the United States to better respond to perceived missile threats from the DPRK, the presidential office in Seoul said on Sunday.

The extended range can now cover all of the DPRK, the ROK's wartime enemy whose arsenal includes intermediate-range ballistic missiles with a range of 3,000 kilometers capable of striking the entire Korean Peninsula as well as U.S. military installations in Japan and Guam.

Calling U.S. alliance with the ROK a "linchpin" of stability in northeast Asia, Carney said "We take seriously our mission of maintaining stability on the Korean Peninsula and in the region."

"The United States remains firmly committed to our alliance and to the defense of the Republic of Korea," he stated, adding "It is absolutely legitimate for the Republic of Korea to take actions in consultation with the United States to respond to a threat posed by the DPRK's ballistic missile program."

The ROK had long called for a revision of the missile pact it signed with Washington in 1979, which stopped the country from developing ballistic missiles of longer ranges despite growing missile threats posed by its northern neighbor.