US rivals, China in particular, are fielding their own fifth-generation fighters, as well as long-range air-to-air missiles that could give Chinese and Russian fighters an advantage over the US in battle.

While range isn't everything, the US is taking steps to maintain its edge through the development of the AIM-260 air-to-air missile, a new, longer-range air-to-air missile that will eventually replace the AIM-120D currently carried by US fighters.

The motivation behind this project, also known as the Joint Air Tactical Missile (JATM), was the Chinese PL-15, a very long-range air-to-air missile carried by a number of fighters, including China's new J-20 stealth fighter.

The US military is developing a new, longer-range air-to-air missile amid growing concerns that China's advanced missiles out range those carried by US fighters.

The AIM-260 air-to-air missile, also known as the Joint Air Tactical Missile (JATM), is intended to replace the AIM-120 Advanced Medium Range Air-to-Air Missiles (AMRAAM) currently carried by US fighters, which has been a go-to weapon for aerial engagements. It "is meant to be the next air-to-air air dominance weapon for our air-to-air fighters," Brig. Gen. Anthony Genatempo, Air Force Weapons Program Executive Officer, told Air Force Magazine.

"It has a range greater than AMRAAM," he further explained, adding that the missile has "different capabilities on-board to go after that specific [next-generation air-dominance] threat set."

Russia and China are developing their own fifth-generation fighters, the Su-57 and J-20 respectively, to compete against the US F-35 Lightning II Joint Strike Fighter, and these two powerful rivals are also developing new, long-range air-to-air missiles.

In particular, the US military is deeply concerned about the Chinese PL-15, an active radar-guided very long range air-to-air missile (VLRAAM) with a suspected range of about 200 km. The Chinese military is also developing another weapon known as the PL-21, which is believed to have a range in excess of 300 km, or about 125 miles.

The PL-15, which has a greater range than the AIM-120D AMRAAM, entered service in 2016, and last year, Chinese J-20 stealth fighters did a air show flyover, during which they showed off their weapons bays loaded with suspected PL-15 missiles.

Genatempo told reporters that the PL-15 was the motivation for the development of the JATM.

The AIM-260, a US Air Force project being carried out in coordination with the Army, the Navy, and Lockheed Martin, will initially be fielded on F-22 Raptors and F/A-18 Hornets and will later arm the F-35. Flight tests will begin in 2021, and the weapon is expected to achieve operational capability the following year.

The US military will stop buying AMRAAMs in 2026, phasing out the weapon that first entered service in the early 1990s for firepower with "longer legs," the general explained.