The U.S. government has asked China to clarify its intentions following the successful test of an anti-satellite weapon last week, that was reported this week by the publication Aviation Week and Space Technology. The State Department has also expressed concern about the space debris that resulted from the missile hit on an old Chinese satellite, saying it could endanger people in space and on the ground. VOA's Al Pessin reports from the Pentagon.

A senior State Department official says the United States wants China to explain why it developed an anti-satellite weapon, calling the move "inconsistent with the constructive relationship" on the use of space agreed to by the two countries' presidents.

The official, who spoke to VOA on condition of anonymity, said the ability to use space is vital to U.S. national security, economic and foreign policy interests. And he said the hundreds of pieces of debris that resulted from the Chinese test endanger other vehicles in space, including manned vehicles, and may endanger people on the ground when they eventually fall to earth.

The official said the Chinese test did not violate any international treaties, but did violate what he called the "the intent and the spirit" of the international Space Treaty, which guarantees free access to space for all peaceful purposes. He said the United States "reserves the right to defend and protect its space systems with a wide range of options from diplomatic to military."

In a VOA interview before the Chinese test was conducted, the head of strategic planning and analysis at the U.S. Air Force Space Command said U.S. policy calls for the protection of the country's access to space. Brigadier General Robert Worley would not discuss any potential threat from any specific countries, but he said the need for free access to space requires his command to consider how to preserve that access. "We all know that there are some actors out there, whether they be nations or non-state actors, that might wish to do us harm in this area. And so we, like any other nation, preserve and reserve the right to take action to prevent people from doing bad things to us," he said.

General Worley says the United States is not interested in developing any space weapons, and may not have to in order to deter attacks on its space assets. The general says the U.S. ability to track everything that happens in space may be enough. "I think there's a significant deterrent effect of everyone knowing that we could attribute a hostile act in space to a particular state or non-state actor," he said.

Still, General Worley acknowledges that Space Command has the responsibility to look at additional ways to prevent attacks on U.S. satellites, ground stations and communications links. He would not provide details. The United States ended its anti-satellite weapon program more than 20 years ago after one successful test. It currently has no space-based weapons or weapons designed to attack targets in space. But experts say a powerful U.S. laser weapon could be used to blind satellites, although it was not developed for that purpose.

The State Department official who spoke Friday said even after the Chinese anti-satellite missile test there is no space weapons race. A spokesman for China's foreign ministry said Friday China also opposes what he called the 'weaponization' of space, and is not looking for a space weapons race. The Chinese spokesman would not confirm the test, but U.S. intelligence and military sources have confirmed it, as have civilian experts who monitor space activity.

Among them is Dean Cheng of the CNA Corporation, an independent research organization. "This test shows that the Chinese have the ability to challenge us in space. The Chinese are a qualitatively different counterpart than any other country is in this regard. I think it definitely requires a response, but I think that the first and foremost response is (to develop) a better understanding of what kind of vulnerabilities we have, given our reliance on space-based systems," he said.

Cheng says the United States should develop a series of backup systems to replace military satellites in case they are destroyed during a war. He says the backups could be aircraft or different satellites in higher orbits.

Cheng says the altitude where China destroyed its satellite, about 800 kilometers high, is used heavily for military purposes including reconnaissance, navigation, remote sensing and earth imaging, as well as for weather satellites which are also important in military planning. He notes that communications satellites and satellites used to detect ballistic missile attacks fly much higher and would not be vulnerable to China's new weapon.

Another space security expert, the Director of the Center for Defense Information, Theresa Hitchens, says the Chinese test should push the United States to negotiate an agreement on the appropriate civilian and military uses of space. "The specter of an all-out war in space, where satellites are being blown up willy-nilly (at will) is incredibly scary. We have the most to lose if space becomes a shooting ground," he said.

Hitchens says a new treaty should include punishment for nations that take inappropriate actions in space, like destroying satellites and littering space with debris. But the State Department official who spoke Friday said the United States is not interested in any additional space treaties that might limit its freedom of action in space.