The Democratic People's Republic of Korea (DPRK) said on Monday its recent missile tests were intended to simulate the launch of tactical nuclear weapons into the Republic of Korea (ROK), a message of deterrence Pyongyang sent following intensified military drills by the ROK and U.S. forces.

The string of ballistic missiles the DPRK fired were part of its military drills designed also to test the preparedness and capabilities of its armed forces, according to state news agency KCNA. The latest missile launch took place on Sunday, the seventh such launch since late September.

Among the targets the DPRK simulated to strike were main ports, military command centers and airports in the ROK, KCNA said.

One of the drills "was aimed at confirming the order of taking tactical nuclear warheads out and transporting them and of managing them in a rapid and safe way at the time of operation, checking the reliability of the overall management system, making the units acquire launching capabilities of the ballistic missile at the underwater silos and inspecting their rapid response posture," KCNA said.

The missile launches were the result of Pyongyang's intention to send a strong warning to its "enemies" after the U.S. sent its nuclear-powered aircraft carrier USS Ronald Reagan to the waters off the Korean Peninsula and the ROK's military chief made "provocative remarks," KCNA said.

DPRK leader Kim Jong Un, who guided the exercises carried out by nuclear tactical operation units, said the "intentional and irresponsible acts" by the U.S. and the ROK "will only invite our greater reaction, and we are always and strictly watching the situation," KCNA reported.

"Even though the enemy continues to talk about dialogue and negotiations, we do not have anything to talk about nor do we feel the need to do so," KCNA quoted Kim as saying.

The DPRK also launched artillery and air force exercises in response to the U.S.'s naval presence in the region. During one of the drills, more than 150 fighter jets took off simultaneously for the first time in history, KCNA said.