The United States sent two supersonic bombers streaking over South Korea on Saturday in a show of military power that underscored rising tensions in the region.

The missiles were fired from a western coastal area around noon and flew towards the country's western sea.

The North has test-fired more than 30 missiles this week, including an intercontinental missile on Thursday that caused an alert in northern Japan, and flew large numbers of warplanes inside its territory in an angry reaction to a massive aerial exercise between the US and South Korea.

F-16 fighter jets and four South Korean F-35s jets were used during the last day of the "Vigilant Storm" air force drills. The deployment of the bombers to the Korean Peninsula was the first in over a year. Fighter jets from both countries took part in the exercise.

The Foreign Ministry of North Korea said the country's military actions this week were an appropriate response to the exercise. North Korea will respond with the toughest counteraction to any attempts by hostile forces to violate its sovereignty.

During previous periods of tension with North Korea, B-1B flyovers were a common show of force. The planes haven't been seen in the region in a while. The United States and South Korea stopped their large-scale exercises to support the former Trump administration's diplomacy with North Korea.

After North Korea increased its weapons testing to a record pace, the allies resumed their large-scale training.

North Korea doesn't like the displays of military might by the Americans. The B-1B was switched from a nuclear strategic bomber to a conventional weapon in the mid 1990s.

The allies decided to extend the training to Saturday in response to a series of North Korean missile launches on Thursday, including an ICBM that caused trains to stop in northern Japan.

The North launched more than 20 missiles on Wednesday, the most in a single day. The launches came after a senior military official in North Korea issued a veiled threat of a nuclear conflict with the US and South Korea.

About 80 military aircraft were scrambled by South Korea on Friday after they tracked about 180 flights by North Korean warplanes. North Korean warplanes were detected in various areas inland and along the country's eastern and western coast, but did not come close to the Koreas' border. There were flight trails from 1 to 5 p.m., but it wasn't clear how many of them were from North Korea.

The Foreign Ministry of North Korea said in a statement on Friday that the United States and South Korea had created a stable atmosphere in the region. The United States used sanctions and military threats to pressure North Korea to give up its nuclear weapons.

The statement said that the provocation was bound to be followed by counter action.

A number of missiles have been launched by North Korea, including multiple ICBMs and an intermediate-range missile. South Korean officials say there's a chance that North Korea will conduct a nuclear test soon. According to experts, North Korea is trying to force the US to accept it as a nuclear power and is also trying to negotiate economic and security concessions from a position of strength.