The White House sought Sunday to limit the impact of a new missile deal with South Korea to its global nonproliferation efforts and regional security conditions in which China plays a growing role.

"The ROK's new missile guidelines are designed to improve the Republic of Korea's ability to defend against DPRK ballistic missiles," White House Press Secretary Jay Carney told reporters.

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

The ROK stands for South Korea's official name, the Republic of Korea, and North Korea's initialization is DPRK, meaning the Democratic People's Republic of Korea.

Carney was responding to a reporter's question as to the South Korean presidential office's announcement hours earlier that Washington has agreed to allow Seoul to develop ballistic missiles with a range of up to 800 kilometers, more than double the current limit of 300km.

It marks the first deal of its kind between the allies in a decade, but the payload cap will remain unchanged at 500kg.

The U.S. government has not made a separate announcement on the missile range agreement. Carney's comments during a routine press briefing were the only formal statement.

South Korea's conservative Lee Myung-bak administration has been pushing to bolster the country's missile capability to counter North Korea's threats.

"As partners whose alliance is a linchpin of stability in northeast Asia, we take seriously our mission of maintaining stability on the Korean Peninsula and in the region," Carney said.

"The United States remains firmly committed to our alliance and to the defense of the Republic of Korea. In this context, we have been in discussions with the Republic of Korea, at its request, on ways to address the threat posed by DPRK ballistic missiles."

It's an open secret that the U.S. had been reluctant to let South Korea sharply increase its ballistic missile range out of concern for a negative effect to its nonproliferation campaign.

The U.S. does not want to antagonize China either.

Under the newly agreed guidelines, South Korea's ballistic missiles will be capable of not only covering all the North Korean regions but also reaching Beijing.

A diplomatic source here said the Obama administration faced a tough choice to accept Seoul's constant request due to the importance of maintaining a robust bilateral alliance.

It is a long-overdue reaction to North Korea's continued provocations such as deadly attacks on the South and long-range missile tests, added the source.

The Chinese government has not issued any immediate response to the news.

China's state news agency, Xinhua, carried articles on the Seoul-Washington move, saying it "runs counter to a global arms control agreement known as the Missile Technology Control Regime (MTCR)."

In 2001, South Korea joined the MTCR, an informal and voluntary partnership among 34 countries to prevent the proliferation of missile and unmanned aerial vehicle technology capable of delivering weapons of mass destruction.

American experts, meanwhile, were split over the revision of South Korea's missile guidelines.

"The reported agreement will enable South Korea to enhance deterrence against North Korea. It also demonstrates the flexibility of the United States in accommodating to the Republic of Korea's unique situation," Richard Bush, a senior researcher at the Brookings Institution, said.

Daryl G. Kimball, the executive director of the Arms Control Association, expressed worries over adverse effects.

"The agreement to allow South Korea to extend the range and increase the payload of its ballistic missiles is a serious mistake because it is unnecessary for South Korea's security and could very easily undermine Asian security for years to come," he said.

He added, "The announcement will also undermine the credibility of the Missile Technology Control Regime (MTCR) and could easily provide the DPRK with a cynical excuse to undertake further provocative actions, including long-range ballistic missile tests or a third nuclear weapon test, in the future." (Yonhap News)