WASHINGTON - The US military needs to better protect its satellites and strengthen its ability to use them as weapons as the uncharted battlefield of space becomes increasingly crowded and dangerous, Pentagon leaders say.

A new military strategy for space, as mapped out by the Pentagon, calls for greater cooperation with other nations on space-based programs to improve America's ability to deter enemies.

"It's a domain, like air, land and sea," said General Kevin Chilton, who led US Strategic Command until he retired late last month. "Space is not just a convenience. It's become a critical part in every other (battlefield) domain."

The US, Chilton said, needs to make sure that it protects and maintains the battlefield capabilities it gets from space-based assets, including global positioning data, missile warning system information, and communications with fighters or unmanned drones that are providing surveillance or firing missiles against the enemy.

As the US and other countries depend more on their satellites for critical data, those assets become greater targets for their enemies.

"It's prudent to anticipate that, at this point, we will not go into a future conflict with a sophisticated adversary and not expect to be challenged in the space domain," Chilton told The Associated Press in an interview. "We need to be thinking about how we would go into future conflicts and make sure that we un-level (that) battlefield in our favor."

While the new strategy - the first of its kind - stresses the peaceful use of space, it also underscores the importance of satellites in both waging and deterring war.

"We need to ensure that we can continue to utilize space to navigate with accuracy, to communicate with certainty, to strike with precision and to see the battlefield with clarity," said William Lynn, deputy defense secretary.

Lynn and other Pentagon leaders say space has become more congested, competitive and contested, and the US needs to keep pace on all fronts.

General James Cartwright, vice-chairman of the Joint Chiefs of Staff, said the US and other nations must develop rules of the road for space that lay out what is acceptable behavior and movement there.

At a forum put on by the Center for Strategic and International Studies, Cartwright said nations need to have guidelines that govern the approximately 22,000 manmade objects orbiting earth, including about 1,100 active satellites.

For example, he said, there is nothing that requires objects to pass left to left, or that says which country should move its satellite if two objects are on a collision course.

While avoiding crashes is an important goal, officials said nations also need to ensure that their communications and other signals passing through the satellites also do not conflict.

The strategy offers little detail about offensive operations in space. But defense officials say that China, Iran and others have demonstrated their abilities to take action in space.The US and Russia had shot down satellites, but the US did it in 1985 with an air-launched missile and the Soviets with a hunter satellite.

According to James Lewis, a national security expert at the Center for Strategic and International Affairs, an attack against US satellites can immediately degrade military performance, taking out communications, data links and other networks needed to operate weapons, sensors and fighters in the air.

"We need some kind of understanding among spacefaring nations about what we can and can't do," Lewis said, adding that a key is to have layers of defense, so there are backups if one set of signals is lost.

The new space strategy, endorsed by top Pentagon and intelligence officials, also shows the importance of having alternatives. For example, if a satellite signal is being jammed, officials should be able to go to another or to an air or sea-based signal.

The US also needs to make it known that even if another nation attacks an American satellite, the US military response wouldn't be limited to a space-based action, officials said. It could turn to any of its warfighting capabilities.