North Korea on Monday accused US spy aircraft of intruding in its airspace recently, warning that there is no guarantee that such aircraft will not be shot down, state media reported.

A spokesperson for North Korea's defense ministry claimed "provocative" flights were made by US reconnaissance aircraft, such as the RC-135, the U-2S and the RQ-4B, over the East Sea and the Yellow Sea from July 2 to Sunday, according to the official Korean Central News Agency.

"Especially in the East Sea, US Air Force strategic reconnaissance aircraft violated the airspace of the Democratic People's Republic of Korea by tens of kilometers several times," the unnamed spokesperson said in a statement carried by the KCNA, using North Korea's official name.

"There is no guarantee that a shocking incident, such as a US Air Force strategic reconnaissance aircraft being shot down over the East Sea, will not happen," the official added.

The spokesperson also slammed the planned US deployment of a nuclear-capable submarine to the Korean Peninsula as a "grave threat" to regional peace.

"The United States' attempt to bring in strategic nuclear weapons into the Korean Peninsula is the most blatant nuclear blackmail against the Democratic People's Republic of Korea and neighboring countries, and is a grave threat and challenge to peace and security in the region and the world," the spokesperson said.

The United States has pledged to send a nuclear-powered ballistic missile submarine to the Korean Peninsula under an agreement reached with South Korea to bolster US deterrence against North Korean threats. The timing of the submarine's deployment has not been revealed. (Yonhap)