Which aircraft is known as the U.S. military's first all-weather fighter?

The F-86 Sabre is recognized as the U.S. military's first all-weather fighter. This distinction stems from its design and capabilities that allowed it to operate effectively under various weather conditions, a significant advancement at the time of its introduction during the Korean War. The F-86 Sabre featured enhancements in avionics and weaponry that contributed to its all-weather operational capability, thus making it a versatile and effective combat aircraft.

In contrast, the F-15 Eagle, while a formidable air superiority fighter with advanced technology, was developed later and does not hold the title of the first all-weather fighter. The F-22 Raptor, introduced in the 21st century, represents the latest in stealth and multi-role capabilities but is not the first all-weather fighter. Similarly, the P-51 Mustang, an iconic aircraft from World War II, was primarily designed for daylight operations and did not have the same level of all-weather capability as the F-86 Sabre.