North Korea stressed Saturday that its latest missile tests are "regular and self-defense" actions against US military threats, taking issue with a UN aviation agency's condemnation of its recent ballistic missile firing.

In a statement, North Korea's National Aviation Administration said, "The missile test launch by the DPRK is a regular and planned self-defensive step for defending the country's security and the regional peace from the US direct military threats that have lasted for more than half a century." The DPRK is the acronym for the North's official name, the Democratic People's Republic of Korea.

The International Civil Aviation Organization, a specialized UN agency handling affairs related to international air navigation, formally described the North's continued launching of ballistic missiles over or near international air routes without prior notice as a serious threat to the safety of civil aviation.

The North, however, claimed its missile testing did not pose any threat or harm to the safety of civilian aviation or neighboring countries.

It made clear that its missile activities are aimed at countering US military threats and criticized the ICAO's move.

"We categorically condemns and rejects this as a political provocation of the US and its vassal forces aimed to infringe upon the sovereignty of the DPRK," the NAA said.

North Korea has ratcheted up tensions on the peninsula with a string of weapons tests, including the firing of an intermediate-range ballistic missile over Japan on Tuesday.

Pyongyang's missile tests are widely viewed as its protest against joint military exercises by South Korea and the US as the Kim Jong-un regime regarded them as a rehearsal for invasion.

The allies staged large-scale annual combined military drills from late August till early September. They also staged joint naval exercises involving a nuclear-powered aircraft carrier, the USS Ronald Reagan, earlier this week in a show of force against the North's provocations. (Yonhap)