On Sunday, the North Korean government said the country had successfully tested a newly developed tactical guided weapon.. The statement comes days after the United States sent advanced fighter jets to South Korea for a joint exercise, AP NEWS reported..

South Korea's Joint Chiefs of Staff said in a statement that it spotted multiple trajectories believed to be North Korean artillery on Sunday afternoon..

The Office of the President of the Republic of Korea reported that the alleged strikes were carried out off the west coast of the DPRK.. Director of National Security Kim Sung Han has checked the readiness of the South Korean military, he said, and his department is closely monitoring the situation..

Last week, six American F-35 fighters from Eielson Air Force Base in Alaska arrived in South Korea for joint exercises with South Korean fighters..

The South Korean Ministry of Defense said the deployment of the fighter jets is aimed at demonstrating a unified allied defense posture and deterring potential external aggression, as well as improving the interoperability of the US and ROK air forces.. The US military said in a statement that US aircraft plan to operate over South Korea and adjacent waters during a planned 10-day training mission..

North Korea usually views joint US-South Korean exercises as a rehearsal for an invasion and responds by testing its own weapons..

The North Korean authorities also said they were forced to develop nuclear weapons in order to cope with US military threats..

Despite a series of missile tests earlier this year, North Korea failed to carry out an expected nuclear bomb test.. Seoul officials believe this is most likely due to the ongoing COVID-19 outbreak and opposition from China, North Korea's last major ally and sponsor..

As previously reported, Russia's aggression against Ukraine has given rogue states a powerful argument to justify building their own nuclear arsenal..