According to the statement of the Korean National Defense Commission on the official Korean Central News Agency (KCNA), Pyongang believed the military exercises were a pretext for war.
"A preventive nuclear strike of justice will be carried out in accordance with the order by the Korean People's Army leadership," the statement said, adding that any military action "bringing down North Korea" will be responded with a "a sacred war of justice."
According to the statement, Pyongyang has a military operation plan to liberate south Korea and strike the United States.
" Offensive means have been deployed to put major strike targets in the operation theaters of South Korea within the firing range and the powerful nuclear strike means targeting the US imperialist aggressor forces bases in the Asia-Pacific region and the US mainland are always ready to fire," the statement read.
On Monday, the US military will start regular exercises in South Korea. Held every two years, the exercise involves US and South Korean troops. The United States stepped up efforts at deploying strategic weaponry in South Korea in response to the North Korean violations of UN resolutions.