Less than two years after the Air Force’s new refueling tanker KC-46A Pegasus made its first flight, the service is already considering acquiring another design and potentially a foreign one, the head of Air Mobility Command said on Wednesday.

“Competition breeds excellence,” Gen. Carlton Everhart II told defense reporters during a breakfast in Washington, D.C. “Competition also drives the price down, so if I can have competitors, I don’t care where they come from.”

The Air Force has 455 tankers in the fleet, including 212 in the active component, 177 in the National Guard and 66 in the Reserve, according to inventory figures provided by Air Mobility Command. The vast majority of those are KC-135 variants, which the KC-46 is intended to replace.

Following KC-X, which became the Boeing Co. KC-46A — a roughly $45 billion program designed to replace a portion of the retiring tanker fleet with 179 new aircraft — the Air Force is expected to launch additional competitions, which could be a part of either the KC-Y or KC-Z programs, respectively, depending on what platforms are offered.

While service officials have hinted a future program may take the shape of an upgraded or modified KC-46 Pegasus, Everhart isn’t ruling out a brand new tanker concept joining its fleet — even from a foreign manufacturer.

Might that mean a foreign tanker joining the U.S. fleet?

“Everything is on the table,” Everhart said. “Now we’ll see if that survives first contact about three miles down that way — in a big white building [that’s] not the White House, but the one with the dome,” he added, referring to Congress.

The command is conducting an assessment to better understand future tanker requirements, the general said last month during the Air Force Association’s Air Warfare Symposium in Orlando, Florida.

The study could also apply to what the next airlifter might look like, he said on Wednesday.

“I am very interested, personally, but I just saw the Green Horizons program that NASA’s put out,” he said, referring to the New Aviation Horizons initiative which aims to accelerate “green,” or environmentally friendly, aviation solutions. The program hopes to sustain future aircraft that burn less fuel and generate 75 percent less pollution per flight, NASA officials have said.

“Hybrid wings, blended wings, I just talked to FedEx, and they’re talking about the same type of technologies out there … because its fuel efficiency, it’s lift capability, allows us to fly faster,” among other things, Everhart said.

The general has prioritized survivability to sustain the command’s tanker fleet, which is a backbone to fighters and bombers operating over hostile airspace in the ongoing campaign against the Islamic State of Iraq and Syria, or ISIS.

For example, one option might be to upgrade a tanker with new technology to minimize its radar cross section, or detectability.

But the technology for tankers wouldn’t necessarily be “stealth” coatings. Everhart recently clarified his comments from last year about a “stealthy tanker” by saying the future tanker fleet could fend off enemy aircraft with what he called “waveform management” to protect radar signatures.

After all, it may be hard for adversaries to spot a fifth-generation stealth fighter but not if it’s refueling from an easily identifiable refueler. Tankers such as KC-135s and KC-10s are first-generation technologies supplying fourth- and fifth-generation fighters.

Enemies “don’t have to look for the fifth-gen, look for the first gen [because if] you take out the tanker, fighters don’t have gas, [the enemy] wins,” Everhart said.

Next-generation technologies will be considered regardless of the path the Air Force takes for a future tanker, whether it’s either an upgraded KC-46 or a new design, the general said.

“Do we bridge — that’s the reason why we may look at a KC-46 Bravo — what are the survivable capabilities for the aircraft, what are the requirements and what do we project the requirements of the world to be?” he said.

But new concepts shouldn’t be ruled out, he added.

“Maybe that’s a 767-300 with a 747 wing, with bigger engines, that’s more efficient, to give me bigger range,” Everhart said.

Once the study is completed, expected this summer, the command will take share the results with contractors to see “what they can do,” Everhart said.

“They’re the ones who’s going to know what’s going to happen in 30 years, or 20 years,” he said, “at least I think they will.”

Editor’s note: This post has been updated to include the latest tanker fleet numbers.