About 1,500 Boeing machinists went on strike Wednesday after last-minute talks broke down between their union and the company unit that operates the Delta rocket program.
A federal mediator was unable to broker an agreement after meeting with both sides Tuesday, the chairman of the union's negotiating committee confirmed.
The strike could affect satellite launch facilities operated by Boeing's Integrated Defense Systems unit at Vandenberg Air Force Base in California and Cape Canaveral in Florida.
Already, the launch of one Delta rocket carrying NASA environmental satellites has been delayed at Vandenberg because of the strike threat.
Two weeks ago, locals with the International Association of Machinists and Aerospace Workers in California, Alabama and Florida, rejected Boeing's latest offer for a three-year contract.
The current three-year contract expired Oct. 23. It covers about 900 workers in Huntington Beach, Torrance, Vandenberg and Edwards Air Force Base in California; about 300 workers at Cape Canaveral in Florida; and about 300 workers at Boeing facilities in Huntsville and Decatur, Alabama, the AP reports.
An intense movement of NATO aircraft was reported at Poland's Rzeszow airfield near the Ukrainian border