South Korea’s air force effectively fired back at North Korea’s missile launch over Japan by conducting a live-fire drill involving powerful bombs, officials said early Tuesday.

Four F-15 fighters dropped eight MK-84 bombs that accurately hit targets at a military field near South Korea’s eastern coast, Seoul’s presidential spokesman Park Su-hyun said.

Each bomb has an explosive yield of a ton, according to the country’s air force.

Park also said South Korean national security director Chung Eui-yong called President Donald Trump’s national security adviser H.R. McMaster to discuss the North’s launch.

North Korea typically reacts with anger to U.S.-South Korean military drills, which are happening now, often testing weapons and threatening Seoul and Washington in its state-controlled media.

But animosity is higher than usual following threats by Trump to unleash “fire and fury” on the North, and Pyongyang’s stated plan to consider firing some of its missiles near Guam.

The Pentagon told reporters it was investigating the launch over Japan, adding: “North American Aerospace Defense Command (NORAD) determined the missile launch from North Korea did not pose a threat to North America.” The U.S. Missile Defense Agency said the Japanese military did not attempt to intercept the missile.

Seoul’s Joint Chiefs of Staff said the missile travelled around 1,677 miles and reached a maximum height of 341 miles as it flew over the northern Japanese island of Hokkaido.

The launch appeared to be the first to cross over Japan since 2009.

The South Korean military said it was analysing the launch with the United States and strengthened its monitoring and preparation in case of further actions from North Korea.

Read more: Fox News