WASHINGTON
 — U.S. President Barack Obama’s recent pledge to seek a ban on space weapons drew a mixed reaction from experts in the field, with some saying the president might be better off pursuing something more modest and less complex, such as a set of international rules governing space operations.

Arms control advocates nonetheless applauded the statement as a welcome departure from the space policy stance of former President George W. Bush, who rejected the notion of banning or limiting space weapons via treaty arrangements.

“The Bush administration rejected space diplomacy,” said Michael Krepon, co-founder of the 
Henry 
L. 
Stimson 
Center
, a think tank here. “We refused to negotiate on any subject that could limit
U.S.
military options. We have a shift from an administration that was very dismissive of multilateral negotiations [as a whole], to an administration that is open to that possibility if it improves 
U.S.
national security.”

Soon after Obama was sworn in Jan. 20, the official White House Web site was updated with a set of policy guidelines including one on restoring
U.S. 
leadership in space. Under the heading “Ensure Freedom of Space,” the statement said the White House would seek a ban on weapons that “interfere with military and commercial satellites”; assess possible threats to U.S. space assets and the best military and diplomatic means for countering them; and seek to assure U.S. access to space-based capabilities, in part by “accelerating programs to harden U.S. satellites against attack.”

Obama’s
campaign in 2008 outlined similar goals, saying an Obama administration would oppose putting weapons in space, seek rules of behavior for spacefaring nations and reduce the vulnerability of
U.S.
space capabilities.

The Bush administration generally opposed international accords that might tie the nation’s hands in space. The National Space Policy issued by the Bush White House in 2006 states in part that the “
United States
will oppose the development of new legal regimes or other restrictions that seek to prohibit or limit
U.S.
access to or use of space.”

Meanwhile, the Pentagon during the past few years carried out or planned a number of experiments that critics charged were thinly veiled tests of space-based weapons. Early last year, with then-President Bush’s approval, the Pentagon downed a wayward
 U.S.
spy satellite using a sea-based missile interceptor.

Experts generally agreed that Obama’s statement signals a new direction in space diplomacy, but some said it does not carry much meaning in the absence of key details, beginning with a good definition of the term space weapon. Coming up with such a definition is complicated by the fact that any number of conventional military and even commercial capabilities can be used to disrupt or damage satellites.

“Obama is delivering on his promise of more cooperation,” said retired U.S. Air Force Lt. Gen. James Armor, former head of the Pentagon’s National Security Space Office. “I like the idea of working together more with our allies, but verification of [a ban on space weapons] is very difficult. If you can’t verify something, it makes it difficult to build a treaty.”

Armor said Obama’s statement could have implications for counterspace operations, which is military parlance for the ability to either disrupt or protect space capabilities. “My sense is this may make it a little harder to do counterspace programs, but we weren’t doing much of any offensive counterspace,” he said. “Most of the Air Force’s efforts are in space situational awareness and defensive counterspace.”

Theresa Hitchens, director of the United Nations Institute for Disarmament Research and a longtime opponent of weapons in space, applauded the White House statement but said that given the difficulty of coming up with an acceptable definition of space weaponry, a better approach would be to seek a ban on certain behaviors.

“I would say this is good starting language,” Hitchens said in an interview. “… The problem is most space technologies have multiple uses, so the approach that should be taken needs to look at actions rather than capabilities. For example, a number of nations use lasers to track satellites, but lasers could also be used to attack satellites in space. So we should focus on outcomes rather than trying to ban certain classes of technology.”

John Sheldon, a fellow at the George C. Marshall Institute here, said arms control agreements are fundamentally flawed and likely to break down at the exact moment they are needed. He said the 
United States 
would do more to protect space security by taking the lead in pressing for informal rules of operation like those used by commercial satellite operators around the world.

“We need to agree on a set of normative practices that will turn into a customary law like we now have on the high seas,” Sheldon said. “Most countries obey the law of the sea based only on centuries of customary practice.”