(CNN) — Seoul, South Korea (CNN) -- North Korea's threatening rhetoric has reached a fever pitch, but the Pentagon and the South Korean government have said it's nothing new.
"We have no indications at this point that it's anything more than warmongering rhetoric," a senior Washington Defense official said late Friday.
The official was not authorized to speak to the media and asked not to be named.
State media: North Korea in 'state of war' with South
The National Security Council, which advises the U.S. president on matters of war, struck a similar cord. Washington finds North Korea's statements "unconstructive," and it does take the threats seriously.
North Korea ready for war? "But, we would also note that North Korea has a long history of bellicose rhetoric and threats, and today's announcement follows that familiar pattern," said Caitlin Hayden, a spokeswoman for the security council.
The United States will continue to update its capabilities against any military threat from the North, which includes plans to deploy missile defense systems.
Pyongyang's propaganda machine flung new insults at the United States on Saturday.
It compared the U.S. mainland with a "boiled pumpkin," unable to endure an attack from a foreign foe, the state-run Korean Central News Agency reported.
North Korea, on the other hand, could sustain an offensive from the outside, the report said. It claimed the government had built shelters around the country "against any enemy nuclear and chemical weapons attack."
The rhetoric and military show of force by the North have heated up in the face of annual joint military exercise between South Korean and U.S. forces called Foal Eagle.
The routine maneuvers are carried out in accordance with the armistice that put an end to armed hostilities in 1953. There was no peace treaty to officially end the war.
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The North Korean government declared the armistice invalid on March 11, 10 days after Foal Eagle began. It is something Pyongyang has done before during heightened tensions.
In an added slap, North Korea has declared that it had entered a "state of war" with neighboring South Korea, according to a report Saturday from the state-run Korean Central News Agency.
"The condition, which was neither war nor peace, has ended," North Korea's government said in a special statement carried by KCNA.
Saturday's reports also asserted any conflict "will not be limited to a local war, but develop into an all-out war, a nuclear war."
The statements made the prospect of war contingent upon "a military provocation ... against the DPRK" in sensitive areas on the border between North and South.
South Korea has not treated its neighbor's latest threat as imminent danger.
Seoul noted scores of its personnel had entered the Kaesong Industrial Complex -- a joint economic cooperation zone between the two Koreas situated on the North's side of the border -- on Saturday morning. Hundreds more were set to join them later in the day, seeming to suggest both sides were going about business as usual.
South officials said that North threats to shut down the complex are part of the North's "measures of putting military alert to highest level," but the South was taking the North's words "seriously," the South Korean Unification Ministry Press Office said.
The threats aren't "beneficial" to the development of the economic zone, the South ministry said. Currently, 310 people work in the industrial complex, the ministry said.
"Our government takes the situation seriously and is prioritizing the safety of our people in Kaesong industrial complex. Our position to maintain stability of Kaesong Industrial Complex remains unchanged," the press office said.
The South hasn't detected, however, any "irregular trend" in the zone, the ministry said.
On Saturday, North Korea attacked that sense of normalcy, questioning the future of the cooperation.
"The entry into the Kaesong Industrial Zone by the south side's personnel has been put in jeopardy," KCNA reported.
The communist government accused Seoul of insulting its dignity with assertions that North Korea would not end the cooperation, because it would be too afraid of losing the revenue it brings.
Pyongyang's declaration it was readying its missiles also did not seem to worry officials in the South.