"Greenpeace opposes star wars because it will ignite a new nuclear arms race," the environmental organization said in the statement.

Some 50 experts on disarmament will gather at the Greenpeace center outside Vandenberg Air Force Base, along with a giant 16-meter (50-foot) inflatable missile and banners reading "Stop Star Wars," the organization said in a press release.

The Pentagon plans to test the national missile defense (NMD) system Friday by attempting to intercept a target missile fired from Vandenberg over the Pacific. The interceptor missile will be fired from the Kwajalein atoll in the Marshall Islands 8,000 kilometers (5,000 miles) away.

The Pentagon's last attempt, on January 18, narrowly missed when the kill vehicle's infrared seekers went on the blink in the final seconds. Its first attempt in October succeeded, although that test was less demanding.

Russia, China, and US allies in Europe have warned that the program could start another arms race and upset the nuclear balance that has kept nuclear war in check for 50 years.