“The arms race into space has already begun.”

WASHINGTON – The successful intercept of a defunct U.S. spy satellite last month revived debate among national security experts about how best to defend the country’s growing number of assets in space.

During a news conference Wednesday, Defense Secretary Robert Gates contrasted the U.S. military’s openness about its Feb. 21 intercept of a defunct spy satellite about 150 miles above Earth with a Chinese mission last year, saying China failed to alert the global community when it hit one of its satellites out of orbit. In addition, the U.S. took measures to limit space debris during the intercept, another difference from the Chinese approach, Gates said.

The China mission caused an international backlash and underscored the vulnerability of U.S. satellites. As the U.S. has increased its reliance on satellites for military and commercial purposes, some in the national security business have questioned the military’s ability to protect the satellites.

“The arms race into space has already begun,” said Jeff Kueter, president of the George C. Marshall Institute, who wrote after China’s missile test that U.S. satellites could be susceptible to a “space Pearl Harbor.”

The U.S. has 443 satellites in orbit with 89 designated for military use, according to the Union of Concerned Scientists’ estimate updated in January. China, in comparison, has 40 satellites in orbit with 13 used for military purposes.

But a March 3 Defense Department report found China spent more than three times its announced defense budget in 2007 and noted that much of that money funded research and development operations.

The Standard Missile-3 used by the U.S. for its Feb. 21 intercept—the first U.S. anti-satellite mission since the Reagan administration—was one of three modified to exceed its conventional range for the mission. The missiles are designed for shorter range air defense to be launched from the sea, said Hans Binnendijk, who studies technology at the National Defense University in Washington.  They would need global positioning systems to hit satellites in higher orbits, Binnendijk said. Most satellites operate in a higher orbit that this type of missile would not be able to hit.

The Chinese test in January 2007 rammed a missile into the target satellite at about 537 miles above ground. Both China and U.S. officials have asked for information about the other’s satellite incept mission, the Associated Press has reported.

Shortly before the U.S. announced it would shoot down a satellite, Russia, which conducted anti-satellite tests in the 1980s, joined with China to present a draft treaty to the United Nations calling for international space disarmament, which the Bush administration rejected.

Experts agreed that the U.S. is heavily reliant on satellites for economic and national security. Satellites can be rendered inoperative without expensive missiles. Kueter, whose institute studies the use of science by the government, said that satellite jamming happens “more regularly than we would like.”

Prior to the Chinese mission, military officials voiced concern over U.S. satellite vulnerability. In testimony before Congress in June 2006, Gen. C. Robert Kehler drew attention to the importance of space as a national security issue.

“Our enemies clearly understand the reliance we place in our space capabilities and we should expect the level and sophistication of efforts to deny us the advantages of space to increase in future conflicts,” Kehler told members of the House Armed Services Committee.

Some experts said the strike proved the U.S.’s anti-satellite potential to China.

“It certainly is plausible that we wanted to demonstrate to China that two can play at this game,” said Ivan Oelrich, who studies nuclear proliferation for the Federation of American Scientists. Oelrich said he believes the U.S. has two options space military policy: give in to an anti-satellite missile ban or try to control space.

“Rather than turning [space] into a commons, we could dominate it,” Oelrich said. “You cannot split the difference.”