The US flew two strategic bombers over the Korean peninsula in a conducted joint military exercise with South Korea.
The B-1B combat bombers, joined by two South Korean F-15K fighter jets, carried out air-to-ground missile drills off South Korean waters. This comes amid heightened tensions with North Korea over its nuclear programme.
In recent months, Pyongyang has conducted its sixth nuclear test and launched two missiles over Japan.
The bombers left from the US Pacific territory of Guam on Tuesday night before entering South Korean airspace and conducting firing exercises over the East Sea and the Yellow Sea, according to South Korea's military.
It added that the training was part of a programme of "extended deterrence" against North Korea. The US said that Japan's air force also took part in the drill.
US President Donald Trump met with top officials from his national security team on Tuesday night for a briefing on ways to respond to threats made from North Korea, said the White House.
Trump and Korean leader Kim Jong-Un have exchanged heated rhetoric in recent weeks. In a speech at the UN in September this year, Mr Trump accused Mr Kim of being "on a suicide mission." Mr Kim responded by vowing to "tame the mentally deranged US dotard with fire."
On Wednesday, a South Korean lawmaker said that North Korean hackers had reportedly stolen a large cache of military documents from his country, including a plan to assassinate Kim Jong-Un, as well as wartime contingency plans drawn up by the US and South Korea.
The South Korean defence ministry has refused to comment on the allegation, while North Korea has denied the claim.