Jim Michaels

USA TODAY

VANDENBERG AIR FORCE BASE, Calif. — The U.S. Air Force successfully tested its second unarmed ballistic missile in a week Thursday night, part of its ongoing effort to demonstrate the accuracy and effectiveness of America’s aging ground-based missiles.

The intercontinental missile blasted out of a silo here shortly after 11 p.m. PST and shot skyward before travelling 4,200 miles in about 30 minutes, landing on target in the ocean near the Kwajalein atoll in the Marshall Islands in the South Pacific.

“The test tonight is one of the ways in which we demonstrate that these missiles are safe and reliable and effective,” Deputy Defense Secretary Robert Work said shortly before the launch.

The Minuteman III missiles, which date to the 1970s, have a range of 6,000 miles and travel at speeds of up to 15,000 miles per hour. Another unarmed Minuteman III missile was launched from Vandenberg Air Force Base over the weekend.

About four missile tests are conducted each year and the tests are publicly announced and closely monitored by other countries.

“Anyone who is a nuclear power is sure to be watching these tests and has to be at least aware that the United States nuclear deterrent is as strong as it has ever been,” Work said.

The test comes as relations between the United States and Russia have worsened and as North Korea is attempting to expand its nuclear capabilities.

The United States has criticized Russia’s military actions in Syria, where it is conducting a bombing campaign aimed at propping up the regime of President Bashar Assad.

Russia is also rapidly modernizing its own nuclear arsenal, said Adm. Cecil Haney, who heads U.S. Strategic Command, and watched the test.