North Korea: UK's Hague calls for calm amid tensions
British Foreign Secretary William Hague has called for calm over the North Korean crisis.
Despite the "paranoid rhetoric" from Pyongyang, it was important to remain "firm and united," he said, warning of the dangers of a "miscalculation" by North Korea.
China's leader Xi Jinping said no country could be allowed to throw the region "into chaos for selfish gains".
North Korea has made a series of direct threats against the US and South Korea.
Since being sanctioned by the UN in March for carrying out a third nuclear test, Pyongyang has threatened nuclear strikes on the US, formally declared war on the South, and pledged to reopen a nuclear reactor in defiance of UN Security Council resolutions.
South Korea announced on Sunday that its top military official Gen Jung Seung-jo, was postponing a trip to Washington, where he was due to meet his US counterpart, because of the rising tensions.
The two sides had decided to reschedule the meeting "to maintain a firm defense readiness amid the current security situation," South Korea's Yonhap news agency quoted a Joint Chiefs of Staff official as saying.
Meanwhile, Switzerland has offered to mediate with North Korea. However, the Swiss foreign ministry says there are currently no plans for any talks.
North Korean leader Kim Jong-un was educated for several years under a pseudonym in traditionally neutral Switzerland, Swiss media say.Missile test postponed
Mr Hague, speaking to the BBC, said: "We have to be concerned about the danger of miscalculation by the North Korean regime".
The foreign secretary said North Korean leaders were making "the wrong choice" between isolation and engagement with the international community, and warned "they will end up leading a broken, friendless country".
But he said there had not been in recent weeks the visible redeployment of ground forces consistent with an invasion plan, nor "a change in what is happening in North Korean society".
On Friday, North Korea warned it would not be able to guarantee the safety of foreign embassy staff in the event of a war.
Mr Hague said he had not seen "any immediate need to respond to that by moving our diplomats out of there" but added that Britain would "keep this under close review with our allies and international partners".
"What is going on is what we have often seen throughout history," he said. "This is a regime that has to justify the intense militarisation of their society."
This week, the North reportedly moved at least one missile to its east coast. It has threatened to strike the Pacific island of Guam, where the US has a military base.
But US and South Korean officials have sought to play down fears of a conflict on the Korean peninsula, saying there are no indications Pyongyang is preparing for a large-scale attack.
Mr Xi, addressing a regional business forum on China's Hainan island, said the international community should advocate security and co-operation, "so as to turn the global village into a big stage for common development rather than an arena where gladiators fight each other".
China is North Korea's only ally and major trading partner, but has grown increasingly frustrated with North Korea's bellicosity.
Mr Xi did not name North Korea directly, but said that "no-one should be allowed to throw the region, or even the whole world, into chaos for selfish gains".
North Korea has not taken direct military action since 2010, when it shelled a South Korean island and killed four people.
This weekend the US said it was postponing a planned test of its own Minuteman 3 ballistic missile, saying it was concerned the launch could be misinterpreted by Pyongyang.
A Pentagon official said the US wanted to avoid any "miscalculation" that might result from the test.
The BBC's John Sudworth in Seoul says Pyongyang will likely use the delay to its advantage in propaganda, and say the US has been forced to climb down in the face of resilience from the North Korean army.
The North Korean media are full of images of military preparedness, he adds, intended to rally people behind the leadership.
Many observers say that North Korea's belligerent rhetoric appears intended for a domestic audience and at shoring up the position of Kim Jong-un, who came to power after his father's death in December 2011.