The US Air Force is buying a new missile as it makes plans to blast through enemy air defenses

• Russia and Ukraine are using their air defenses to deny each other control of the air.
• As a result, their ground forces are fighting without the benefit of air superiority.

The Russian and Ukrainian air forces have played a relatively minor role in the war in Ukraine. Both sides have tended to keep their aircraft over friendly territory rather than risk tangling with sophisticated enemy air defenses, such as Ukraine's US-made Patriot and Russia's S-400.

That's an ominous sign for the US military, which has relied on the flexibility and lethality of its airpower since World War II. If aircraft can't weaken the enemy, then ground troops have to do all the work, and that means more casualties.

"I think most folks thought that this war would be over in two weeks, maybe a month, and here we are 18 months later, and it's still going on," Gen. James Hecker, the commander of US Air Forces in Europe, said at the Air and Space Forces Association conference in September.

The reason for that duration was that "neither side has been able to gain air superiority," Hecker added. "This is a fight that we don't want to fight."

One way to avoid a Ukraine-like aerial stalemate is to smash the enemy's air defenses, especially their radars. That's why the US Air Force is developing a stand-off antiradar missile. It just awarded a $705 million contract to Northrop Grumman for the Stand-in Attack Weapon, or SiAW. The missile is scheduled to be deployed around 2026.

Essentially, the SiAW seems to be the latest iteration of antiradar missiles that have been around since the 1960s and that work by homing in on beams from radar transmitters.

Early models, such as the US's AGM-45 Shrike, were only moderately effective in the Vietnam and Arab-Israeli wars, where the missile could lose lock-on if the radar was turned off. But the later AGM-88 High-Speed Anti-Radiation supersonic missile, known as HARM, was devastating in Wild Weasel missions against Iraqi air defenses during Operation Desert Storm.

The US has given HARMs to Ukraine and helped the Ukrainians modify their Russian-designed MiG-29 fighters to work with the US-made missile.

The US military uses the AGM-88E Advanced Anti-Radiation Guided Missile, or AARGM, which is an upgraded HARM. An extended-range AARGM-ER is in development.

One key question will be SiAW's range. When aircraft stalk antiaircraft weapons, prudence dictates they stay as far away as possible. While the HARM has a range of about 30 miles, depending on launch altitude, the AARGM reportedly has a range of 60 miles to 80 miles, and the AARGM-ER of more than 100 miles. An S-400 antiaircraft missile has a range of up to roughly 250 miles.

Details on SiAW are sparse, though Northrop Grumman describes it as a "tail controlled missile for increased maneuverability and survivability." But the new missile is likely to have a longer range and higher speed than the various HARM models, which have a speed of about Mach 2.

"The SiAW will have multiple seeker sensors and use GPS in addition to other navigational systems," Air and Space Forces Magazine reported.

The magazine also noted that "despite the weapon's longer range, the term 'stand-in' indicates that it operates within an enemy's defended airspace," which suggests a shorter range than stand-off missiles such as the Joint Air-to-Surface Standoff Missile-Extended Range cruise missile, with a reach of about 600 miles.

What's also notable is SiAW is meant to be more than an air-defense killer. The Air Force wants a munition that can destroy enemy missile launchers — including those of antiaircraft, cruise, and antiship missiles — as well as GPS jamming stations and antisatellite installations. This suggests SiAW will have a sophisticated guidance system that is either on-board or data-linked to other sensors, or both.

Also significant is that SiAW is expressly designed to fit inside the F-35's internal bomb bay rather than mounted externally. This will limit the size of the missile.

The ultimate prize here is countering anti-access/aerial-denial, or A2/AD, networks. If Russian and Chinese air defenses — or perhaps those of Iran and North Korea — can use long-range air-defense radars and missiles effectively, then US aircraft will face a choice between staying out of range — and thus not performing their missions — and going in at the risk of prohibitive losses.

If successful, SiAW may spare American commanders that hard choice.

"I think a lot of the other services assume that they're going to have air superiority like they've had for the last 30 years," Hecker said at the conference. "Well, that was an uncontested environment, and this is not an uncontested environment. So we're going to make sure we're ready for that fight and that we can gain air superiority through counter-A2/AD."

Michael Peck is a defense writer whose work has appeared in Forbes, Defense News, Foreign Policy magazine, and other publications. He holds a master's in political science. Follow him on Twitter and LinkedIn.