It is described by the United States Air Force as the modern backbone of America's long-range bomber force, built for low-level, high-speed missions.

BBC: Profile: B-1 bomber

Although the number of F-22 fighters was capped at 187, the Air Force would increase its long-range strike capabilities by 50 percent and the penetrating component of long-range strike by a factor of five by 2025.

CENTERFORSECURITYPOLICY: Center for Security Policy | The Measure of a Superpower: A Two Major Regional Contingency Military for the 21st Century | Page: 2

Having recently reversed himself on the bomber and approved Air Force plans to develop a new long-range strike aircraft, the defense secretary needs to also revisit his decision on F-22.

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So with their aging fleet of barely 160 long-range bombers facing a growing array of operational challenges, Air Force leaders have reluctantly come to the conclusion that they need to buy a new bomber.

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Artillery was gradually replaced by tactical missiles in the defensive role, but the Air Force was too busy building a fleet of long-range bombers and supersonic fighters to be bothered with ground-based air defenses, while Army troops had a clear need for such defenses.

FORBES: Missile Defense Becomes A Navy Mission