North Korea has warned any U.S. attempt to intercept its missile tests would be treated as a "declaration of war."
Pyongyang also blamed joint military exercises between the United States and South Korea for growing tensions, state media KCNA said Tuesday.
Kim Yo Jong, the powerful sister of leader Kim Jong Un, warned in a statement that Pyongyang would see it as a "declaration of war" if the U.S. took military action against the North's strategic weapon tests.
She also hinted that the North could fire more missiles into the Pacific Ocean. The United States and its allies have never shot down North Korean ballistic missiles, which are banned by the United Nations Security Council, but the question drew new scrutiny since the North suggested it will fire more missiles over Japan.
"The Pacific Ocean does not belong to the dominium of the U.S. or Japan," Kim said.
Analysts have said that if North Korea follows through on its threat to turn the Pacific Ocean into a "firing range," it would allow the isolated and nuclear-armed state to make technical advances in addition to signaling its military resolve.
In a separate statement, the chief of the Foreign News Section at North Korea's Foreign Ministry accused the U.S. of "aggravating" the situation by conducting a joint air drill with a B-52 bomber on Monday and planning U.S.-South Korea field exercises.
In response, South Korea's Unification Ministry, which handles relations with the North, said Pyongyang's "reckless nuclear and missile development" is to blame for the deteriorating situation.
The United States deployed the B-52 bomber for a joint drill with South Korean fighter jets, in what South Korea's Defense Ministry said was a show of force against North Korea's nuclear and missile threats.
The two countries will conduct more than 10 days of large-scale military exercises known as the "Freedom Shield" drills starting next week.
On Tuesday, U.S. and South Korean warplanes practiced quickly taking off in a drill designed in response to North Korean threats to destroy airfields, Yonhap news agency reported.
Around 28,500 U.S. troops are stationed in South Korea as a legacy of the 1950-1953 Korean War, which ended in an armistice, rather than a peace treaty, leaving the countries technically at war.
