Missing plane `has no link with Oklahoma bomb'

With rumours still flying thick and fast about the mysterious disappearance of an A-10 fighter plane over the western United States, no less a figure than the chairman of the armed forces chiefs of staff, General John Shalikashvili, has found it necessary to reject one of the more bizarre theories advanced.

The four-star general, the Pentagon's most senior military officer, said he had been following the search for the plane with interest, but did not see any connection between the missing plane and the bombing of the federal building in Oklahoma City two years ago. "I do not have enough information," he said, "to lead me to believe that there's somehow a connection between that incident in Oklahoma City ... and the disappearance of this airplane."

Gen Shalikashvili did, however, say that security was being increased around the Denver courthouse, where jury selection is in progress for the trial of Timothy McVeigh, the man accused of masterminding the bombing. Today is the second anniversary of the attack, which killed 168 people, and also the fourth anniversary of the Waco disaster, in which 80 people died when FBI officers tried to storm the Branch Davidian compound.

Intriguingly, the general also confirmed that additional security measures had been introduced at the North American Aerospace Defence Command in Colorado because there had been "an indication" of a security threat to the installation.

General Shalikashvili's denial was a response to speculation that the pilot of the missing A-10, Captain Craig Button, stole the plane - which was armed with four bombs - in order to stage some spectacular action for the Oklahoma City anniversary. This theory assumes that Capt Button may have sympathised with the illegal right-wing militia group with which Timothy McVeigh was supposedly involved - something that has been vigorously denied by those who knew him.

Theories such as this, and the even more far-fetched idea that Capt Button's A-10 might have been abducted by aliens, proliferate on the Internet. The problem for the military is that information about heightened security seems only to support the theories, and as yet the air force has been able to produce no compelling evidence to refute them.

Despite deploying the most sophisticated search techniques, including U2 spy planes and AWACS aircraft, it has failed to trace the plane, which went missing on 2 April after breaking away from a routine training exercise over Arizona. Air force officials blame the thick snow in the region of Eagle, Colorado, where some say they heard a possible plane crash at the time the plane would have run out of fuel. The air force now says, however, that it has no "seismic indications" of a crash in the area and will call off the search until the snow melts if nothing is found by Tuesday.