Some Newtown workers will be offered jobs in Denver, which will be hiring about 350 people, said Lockheed spokesman Chip Eschenfelder.
"In the face of government budget cuts and an increasingly complex global security landscape," Lockheed Martin president and CEO Marilyn Hewson said, "these actions are necessary for the future of our business."
The software-development work for military sensoring-communications systems currently done in Goodyear will be moved to Lockheed locations in Valley Forge and Denver, the company said.
"As the transition progresses, we'll determine whether employees will be added" in Valley Forge, where about 2,700 now work, said Lockheed spokeswoman Suzanne Smith.
Sitting at a bar a few miles from Lockheed's Newtown site, two engineers in their 30s said they were still processing the news, feeling shock, disappointment, and the weight of several unanswered questions.
The two men - and more than 20 coworkers sitting nearby at Isaac Newton's - technically still had their jobs. They knew only that the entire plant would close within 18 months and that only some of them would be offered jobs in Denver.
Most declined to speak, and the two engineers declined to give their names.
"It's disappointing for me, because it's a job I've had for several years," said one, drinking a craft beer. "Am I concerned? I don't know yet. I'm mostly hoping I get an offer out there" in Denver.
If offered a job in Denver, the engineer said, his wife would be willing to move. Not all of his coworkers would have that option. For many, the only comparable company in the region is Boeing.
"I knew there was going to be a downturn," the other engineer said. "But I didn't envision the plant being closed down."
Since 2008, Lockheed Martin, the 19th-largest employer in Bucks County, has reduced overhead costs, cut capital expenses, removed 1.5 million square feet of facility space, and reduced its workforce from 146,000 employees to 116,000. The company's 2012 net sales were $47.2 billion.
U.S. Rep. Mike Fitzpatrick (R., Bucks) said Lockheed's decision was "incredibly disappointing. I feel deeply for the hundreds of families whose outlook has become uncertain."
Fitzpatrick said he had contacted Lockheed and "implored" the "appropriators" in the government to do something to keep Newtown open.
State Rep. Steve Santarsiero (D., Bucks) said the closing "will have a ripple effect" in neighborhoods. He called on colleagues to try to reverse the decision and, if unsuccessful, to "support a transition for the families," while at the same time recruiting other industries to the area.
This month, 240 workers at Lockheed Martin's facility in Moorestown received layoff notices, effective next Wednesday. About 3,500 will remain at the Burlington County site, said Lockheed spokesman Keith Little.
The Moorestown facility is best known for its development of the Aegis air-defense combat system for the Navy to detect and destroy incoming missiles.