North Korea's labor union on Sunday vehemently denounced the United States and South Korea's President Park Geun-hye for carrying out military drills targeting key facilities and the leadership of the communist country.

"On behalf of all the workers, the U.S. imperialists and the Park Geun Hye group of traitors of South Korea for their heinous moves to get the sun eclipsed, not content with running amuck in the reckless moves to invade the DPRK," the statement released by the spokesman for the Central Committee of the General Federation of Trade Unions of Korea (GFTUK) said.

It said if the "enemies ignite a war, the DPRK's working class will join the powerful revolutionary Paektusan army in the battle to blow up the den of the Park's regime, liberate the southern part of Korea and build a new society for the working people there, tightly holding arms of the revolution instead of hammer."

The DPRK stands for the Democratic People's Republic of Korea, the North's official name, while the Paektusan army named after the highest peak in the country refers to the military.

The GFTUK then claimed the world at large will see how the service personnel and people of the DPRK, including the working class, firmly rally behind the country's leadership and move to strike all those that provoke the country.

It said the country will eventually win the final confrontation with the United States and achieve national reunification, while Park and her followers will pay the price for their actions.

The North has come under increasing pressure from the international community for carrying out its fourth nuclear test in January and firing off a long-range missile the following month.

The United Nations has slapped its toughest ever sanctions on the country in response.

The North fired out both short-range and medium-range missiles in defiance, and on Saturday, its military threatened to take "merciless" action against South Korea unless Seoul apologizes for its alleged move to hurt the dignity of North Korean leader Kim Jong-un.

It also demanded Seoul punish all those who plotted to strike the North Korean leadership, claiming that it is the last opportunity for Cheong Wa Dae, South Korea's presidential office, to avoid retaliatory attacks.

Related to the rise in threats and verbal assault made on the South in recent weeks, North Korean watchers said various organizations in the North seem to be competing with each other to show their loyalty to the country's leadership.

"The organizations and the military, by making threats and blasting the South, are showing that they are loyal to North Korean leader Kim Jong-un," said Yang Moo-jin, a professor at the University of North Korean Studies.

He said such actions serve to enhance the internal cohesion of the isolationist country.

Kim Yong-hyun, a professor of North Korean studies at Dongguk University, said that the North's move to ratchet up its war of words may be to show that it still wants to control key issues as tensions mount on the Korean Peninsula. (Yonhap)