North Korea has rounded off a week of bellicose rhetoric by warning that it has entered a "state of war" with South Korea, in a new blow to relations on the Korean peninsula.
The statement on Saturday – which follows other provocative announcements in recent days – drew a calm response from the South Korean public, which is accustomed to such language.
But analysts warned that it would be difficult for either Pyongyang or Seoul to ratchet down the high level of tension on the peninsula, which has been divided since the Korean war.
North Korean state media has spent several weeks fiercely condemning current US-South Korea joint military exercises and UN sanctions that followed its nuclear test last month.
As part of the exercises, the Pentagon this week dispatched two nuclear-capable B-2 stealth bombers from the US to the Korean peninsula, in a demonstration of American military might.
In response to these and B-52 bomber sorties, Pyongyang on Saturday said US behaviour had "entered the reckless phase of an actual war".
Despite the aggressive rhetoric, North Korea's threat was couched in conditional language. The statement issued by KCNA, the state media agency, said: "If the US and the South Korean puppet group perpetrate a military provocation for igniting a war, [it will] develop into an all-out war, a nuclear war."
The defensive nature of the warning accords with a consensus among analysts that North Korea would be unlikely to initiate a war, given the technological inferiority of its military resources to those of the US. For decades, anti-US propaganda has been a staple theme of North Korean efforts to boost patriotic feeling.
"I think it's in the context of deterrence, with a lot of it directed at the domestic audience," said Daniel Pinkston, a North Korea expert at the International Crisis Group. "With the ongoing exercises, the leadership needs to look strong in the face of external threats – real or perceived – or else run the risk of looking weak internally."
The tensions have given Kim Jong-eun an opportunity to burnish his credentials as a military leader, 15 months after he succeeded his father Kim Jong-il.
State media has portrayed Mr Kim sternly issuing orders to his top generals and visiting front-line military units. He has placed missile units on the highest levels of readiness, while ordering the military to target South Korean islands off the west coast of the Korean peninsula.
"I'm getting a bit more concerned about something going on in the West Sea," said Bruce Klingner, an analyst at the Heritage Foundation.
Mr Klingner cited the precedent of North Korea's bombardment of Yeonpyeong Island in 2010, which North Korea justified by citing South Korea's shelling of disputed waters during a military exercise. He said Seoul's restrained response at the time – which was limited to shelling some North Korean artillery positions – might embolden North Korea to consider a similar attack.
However, South Korea's new government under President Park Geun-hye has promised a tough response to any North Korean provocation, and a bilateral pact signed with Washington on Monday guarantees US support in such a scenario.
The Yeonpyeong attack caught Seoul off guard because it was not preceded by intense threats of war. Pyongyang has surrendered any element of surprise with its recent rhetoric.
North Korea's warning on Saturday that "the state of neither peace nor war has ended" appears to tally with the assessment of one US veteran of talks with the country: that it wants to agree a formal peace treaty to replace the 1953 armistice that ended the Korean war. Pyongyang this month repeated a 2009 statement that it no longer recognised the armistice as valid.
However, Ms Park, who was recently elected president, has said that Seoul does not consider a peace treaty an end in itself.
Moon Chung-in, a professor at Yonsei University who participated in talks with the North under two South Korean governments, said diplomatic engagement with Pyongyang was the only way to calm relations.
North Korea appeared to view an attack by the US as a real possibility, he added.
The last US agreement with North Korea – a February 2012 deal that saw Pyongyang agree to suspend its nuclear programme in exchange for aid – broke down less than two months later when North Korea attempted a rocket launch.
The resultant distrust of Pyongyang weakened the likelihood of Washington taking the initiative on engagement, Mr Moon said. "I hope Park Geun-hye's government will use this situation to make some sort of move."
