Northrop Grumman Corp, maker of the stealth B-2 bomber, beat out a Boeing Co and Lockheed Martin Corp team to develop and build a next-generation long-range strike bomber, the US Defense Department said on Tuesday.The announcement ended months of anticipation and marked the biggest contract award by the Pentagon in over a decade, a deal analysts have said could be valued at up to $80 billion if the US Air Force buys all 100 stealth bombers now planned.But Boeing told employees late Tuesday it would "rigorously deliberate whether to protest" the contract award, which could delay any work on the program for 100 days.Air Force Assistant Secretary Bill LaPlante told reporters the service hoped to beat independent estimates, which forecast that it will cost $23.5 billion in fiscal 2016 dollars to develop the new bomber. The aircraft, costing an average of $564 million to build, will be able to deliver both conventional and nuclear weapons."Building this bomber is a strategic investment in the next 50 years," US Defense Secretary Ash Carter told reporters. "It demonstrates our commitment to our allies and our determination to potential adversaries, making it crystal clear that the United States will continue to retain the ability to project power throughout the globe long into the future."The bomber is slated to be ready for initial combat use by 2025.