(CNN) -- North Korea said Saturday any sanctions or pressure applied against it following its rocket launch earlier this month will be considered a "declaration of war."
A North Korean soldier looks into South Korea from the demilitarized zone on April 9.
In an announcement on state-run television, the country said it was ready to step up efforts to develop nuclear weapons and poised for a military response to any moves against it.
"The revolutionary armed forces of the DPRK are always keeping themselves fully ready to go into action any moment to mercilessly punish anyone who encroaches upon the sovereignty and dignity of the DPRK even a bit," it said.
On Monday the United Nations condemned North Korea -- which refers to itself as the Democratic People's Republic of Korea, or DPRK -- for launching a rocket.
The United States called the launch a "provocative act" that violated a 2006 Security Council resolution prohibiting Pyongyang from conducting ballistic missile launches.
Pyongyang insists the April 5 launch was a successful mission to place a communications satellite into orbit. The United States says the rocket's payload did not reach orbit.
The U.N. statement says the rocket launch was "in contravention" to a 2006 Security Council resolution that demanded that North Korea not launch any ballistic missiles.
The 15-member council also voted unanimously for a statement by the council's president demanding the country make no more launches.
"The Korean People's Army will consider sanctions to be applied against the DPRK under various names over its satellite launch or any pressure to be put upon it through 'total participation' in the PSI (Proliferation Security Initiative) as a declaration of undisguised confrontation and a declaration of a war against the DPRK," the announcement on state TV said.
"Now that the group officially declared confrontation and war against the DPRK, its revolutionary armed forces will opt for increasing the nation's defense capability including nuclear deterrent in every way, without being bound to the agreement adopted at the six-party talks," it continued, apparently referring to the Security Council.
Referring to South Korean President Lee Myung-bak, the statement added, "The Lee group of traitors should never forget that Seoul is just 50 kilometers (31 miles) away from the Military Demarcation Line."
That line was established by the 1953 Armistice Agreement between the two Koreas -- which are still technically at war.
A Friday report North Korea's official KCNA news agency, seemed to blame the "war hysteria" on the United States and South Korea after the two countries carried out a combined air force operation in South Korea.
The "'South Korea-U.S. military alliance' oft-repeated by them is, in essence, nothing but a 'war alliance' and 'alliance for aggression' aimed at invading the DPRK," the report said.
"When a nuclear war will break out due to the war chariot of the 'South Korea-U.S. military alliance' is a matter of time," it said. "The U.S. and South Korean warmongers would be well advised to stop acting rashly, properly understanding who their rival is."