South Korea’s deal to allow North Korean athletes and dignitaries to attend the Winter Olympics in PyeongChang appeared to ease tensions on the peninsula earlier this month. Still, it appears the US air force has been expanding its presence in South Korea.

Local media reported Monday that an EC-130H Compass Call aircraft, an advanced plane capable of denial of service attacks on enemy plane’s communication systems, was deployed to South Korea’s Osan Air Force Base by the US Air Force earlier this month.

According to Sputnik, it’s unclear why the state-of-the-art tactical aircraft was deployed to the base. Some critics have speculated that it may be used to collect data on North Korea’s military during the Games, which are set to begin Feb. 9.

The plane, based at Arizona’s Davis-Monthan Air Force Base, the aircraft reportedly made its way to South Korea after stopping at Japan’s Yokota Air Base.

The US Airforce only has 14 of these advanced aircraft in its entire arsenal, according to Sputnik.

The planes have recently been used to keep Daesh fighters from coordinating attacks.

“If we can shut down or deny their communication,” Lt. Col. Chris Weaton of the Electronic Combat Squadron said in a statement, “then we are causing chaos.”

An estimated four of the 13 EC-130Hs are operating in Iraq and Syria.