Media analysis: The North Korea threat
North Korea has issued a torrent of belligerent threats against the US and South Korea in recent weeks.
North Korea launched a rocket in December and conducted its third underground nuclear test in February.
These actions led to international condemnation and stiffer sanctions, further provoking Pyongyang.
Analysts have been assessing how close the peninsula is to an outbreak of military hostilities, and possible action by the international community.
To long-time North Korea watchers, there is a numbing sense of deja-vu with the current crisis, writes Barabara Demick in the LA Times.
One of the big unknowns this time, however, is Kim Jong-un, who has only been in power since December 2011. The fear is that the young, untested leader might actually believe his country's own inflated rhetoric about how powerful it is, writes Ms Demick.
There appears to be a general consensus that this crisis will almost certainly not peak with North Korea deciding to launch a full-scale war.
Instead, the big risk is that a small incident could trigger an escalation that runs out of control, writes David Blair, chief foreign correspondent for the UK's Daily Telegraph newspaper.
John Swenson-Wright writes in Prospect magazine that the young leader is artfully playing a long game of diplomatic chess in which Pyongyang appears to be several moves ahead of the international community.
Mr Swenson-Wright says there are a number of domestic and international objectives behind Pyongyang's provocations but "the underpinning reason is a powerful desire by the North to force the Obama administration to engage in direct and public negotiations.
"Washington, wedded to a policy of 'strategic patience' that seeks to contain North Korea without rewarding it for its bad behaviour, has resolutely resisted."
He says it is especially urgent for the US to recapture the initiative in this diplomatic tussle of wills.
Last week, the new US defence secretary Chuck Hagel ordered America's most advanced plane, the B-2 stealth bomber, over the Korean peninsula for the first time.
The message to North Korea was intended by the Pentagon to be one not of provocation but deterrence, writes The Guardian's Ewen MacAskill in Washington: Attack South Korea at your peril.
The US military has moved ships and planes toward South Korea, relocated artillery battalions and cancelled military leave as a precaution.
Kurt Campbell, who until recently was assistant secretary of state for East Asian and Pacific affairs, told the Wall Street Journal: "The North Koreans have been very careful. They know exactly how to walk right up to the wire yet not trigger a crisis."
The danger, he says, is that the Korean peninsula is so heavily militarized that "one miscalculation could lead to a tragedy", and that South Korea is less willing than before to simply accept North Korean provocations without reacting.
RUSI's Andrea Berger says one suggestion for policy-makers in response to current developments could be to pursue talks, not necessarily negotiations. Without any kind of dialogue misperception, miscalculation is a much greater possibility.