President Donald Trump warned North Korea on Tuesday, saying America is prepared to use “devastating” military action if necessary, CNN reports.

The warning comes after the rogue nation reportedly moved a small number of fighter jets, external fuel tanks and air-to-air missiles to a base on its eastern coast.

U.S. satellite imagery captured the move, which is viewed by the United States as an effort to boost military readiness. So far, some missiles and fuel tanks are on the Mig-29 aircrafts, but no single jet is carrying both external fuel tanks and missiles.

On Monday, Ri Yong Ho, who serves as North Korea’s foreign minister, claimed that Trump has “declared a war” on the country. He threatened to shoot down U.S. aircraft flying off its coastline despite them being in international airspace.

In response to Pyongyang’s “reckless behavior,” America flew B-1B bombers from Guam in international airspace just east of North Korea on Saturday, U.S. defense officials said.

Defense officials also said that America maintains the necessary aerial surveillance and radar capability in the region to determine if any military aircraft take off from the country.

In a joint news conference with Spanish Prime Minister Mariano Rajoy, Trump stressed that the U.S. is “totally prepared” to use the military option, if necessary.

“If we take that option it will be devastating—devastating—for North Korea,” Trump said. “It’s called the military option.”
Trump also made remarks regarding North Korea’s leader, Kim Jong Un. “He’s acting very badly. He’s saying things that should never ever be said,” he said.
The president also insisted his replies were exclusively in response to rhetoric from North Korea.
“I’ll fix the mess,” Trump said. “We’ll see what happens.”