Tens of thousands of North Korean soldiers and civilians held a huge rally and march in Pyongyang on Friday, in a mass display of support for a possible military strike against the United States.

The rally in Pyongyang's giant Kim Il-Sung square was attended by soldiers, veterans, workers and students, all wearing military uniforms. The North's young leader, Kim Jong-Un, was not present.

State television said the rally took place to support a decision issued by the Korean People's Army (KPA) supreme command on Tuesday -- and ratified by Kim on Friday -- to put the country's strategic rocket units on a war footing.

"The statement was the ultimatum of the Korean People's Army against the US imperialists," an announcer said at the start of the rally.

Under giant portraits of Kim's father Kim Jong-Il and grandfather Kim Il-Sung, the massed ranks of civilians and soldiers pledged their allegiance to the current leadership.

"Let's become guns and bombs for our respected leader Kim Jong-Un!," they chanted, pumping their fists in unison.

The rally was addressed by military and party officials who urged North Korean troops to launch a "merciless strike" on the US mainland and US military bases in the Pacific and South Korea.

"We are all ready to wipe them out for our final victory," army officer Kwon Yong-Chol said.