The Pentagon will no longer allow personnel to travel to tradeshows and conferences amid the Omicron coronavirus spike. "The only travel that is permitted is what's considered critical to national security,” Pentagon Press Secretary John Kirby said Tuesday. “So participation in conferences is obviously put on hold. And that applies to everybody, uniformed and civilian alike.” The travel restrictions come in advance of several conferences scheduled in the coming months, including the Singapore Air Show (Feb. 15 to 18); Air Force Association Warfare Symposium in Orlando, Florida (March 2 to 4); Association of the U.S. Army Global Force Symposium in…