The cracks were in the upper longerons - parts near the canopy - on two of the aircraft, which were among 30 inspected F-15s deployed at the Kadena Air base on Japan's southern island of Okinawa, the Air Force said.

The Air Force issued a second flight suspension order for the fighters worldwide since a F-15C crashed in Missouri last month, injuring its pilot.

The Air Force said the F-15s will not return to operation until analysis, as well as necessary inspections and repairs are completed.

Japan's Air Self-Defense Force said its inspection of all its roughly 200 F-15 jets since the crash has found no problems.

More than 700 F-15s are in its worldwide inventory, according the Air Force. F-15s fly from bases in the U.S., England, Japan and the Middle East.

The U.S. Air Force has been using the F-15 since the mid-1970s. The fleet is currently being replaced by the F-22 Raptor, but F-15s still make up a significant percentage of its fighter jets.

The U.S. military, which occupies large parts of Okinawa under the bilateral security pact, has F-15s at their bases.

Okinawa is about 1,000 miles southwest of Tokyo.

Sound Off...What do you think? Join the discussion.

Copyright 2009 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

More Military Headlines

• South Korean Air Force Modernizes
• Block 40 Global Hawk Faces Hurdles
• AF General Takes Charge of SouthCom
• Airmen Rescue Kittens Inside Wall
• Airmen Rescue Kittens Inside Wall