The interception of a “disabled spy satellite” by a Pentagon missile is worrying some countries that see it as a poorly disguised attempt to test an anti-satellite weapons system. The Pentagon missile launch Thursday amounted to an unprecedented demonstration to the world that the U.S. can take out spacecrafts launched by other nations.

The Pentagon said Feb. 21 that a U.S. missile smashed a disabled spy satellite that was headed for earth with a load of toxic fuel on board but wouldn’t rule out that toxic materials would land somewhere on earth. A spokesman said “nothing larger than a football” had been tracked so far.

Almost immediately after the reported “success” China said it was on the alert for possible harmful fallout from the shoot-down and urged the U.S. to quickly release data on the action.

Pentagon officials are saying the strike was a one time only incident but are well aware that because of it they will amass huge amounts of data that they can use to improve weapons technologies that make use of sophisticated missiles.

They used the USS Lake Erie, armed with SM-3 missiles designed to knock down incoming missiles, not orbiting communication or spy satellites. This amounted to a test of the weapons system and a confirmation that the system can take out an incoming missile traveling at 17,000 m.p.h., the speed at which the satellite was traveling. It also resulted in the Pentagon being able to confirm that it can use its “defensive” missiles to target satellites that other countries have put into orbit. The missile strike, which was approved by President Bush, blurs the lines between defending against a hostile long range missile and targeting another country’s satellite in orbit.

The Chinese have also reacted to this aspect of the missile strike.

“China is continuously following closely the possible harm caused by the U.S. action to outer space security and relevant countries,” Foreign Ministry spokesperson Liu Jianchao said at a news conference in Beijing. “China requests the U.S. to fulfill its international obligations in real earnest and provide to the international community necessary information and relevant data in a timely and prompt way so that relevant countries can take precautions.”

While the missile strike yields tons of data as a weapons test, its success in preventing the fall of toxic fuel to earth is less certain.

Marine Gen. James Cartwright, vice chair of the Joint Chiefs of Staff, told a press conference Thursday that officials “have a high degree of confidence” but wouldn’t say for sure that the missile hit the satellite’s fuel tank. Destroying the fuel was the original announced purpose of the mission.

U.S. officials have said the fuel would pose a potential health hazard to people if it landed in a populated area. They say it might take a day or longer to know for sure if the toxic fuel was blown up and that “hazardous materials teams” will be flown to the site of any dangerous debris that might land in the United States or anywhere else.