Ten days ago, experts were saying there was basically nothing to worry about with North Korea, that what we were experiencing was the usual bombast and bloodcurdling rhetoric that we've heard before.

Now, those experts aren't so sure. Kim has gotten himself so far out on a limb, that unless he makes good in some way on his threats, he will lose face with the leadership clique that runs the country and could be in trouble.

And "making good" might lead to conflict.

How might a new Korean war start?

Patrick Cronin:

Let's say that the North decides to fire its new mobile KN-08 intermediate-range ballistic missile, capable of reaching U.S. bases in Guam. An X-band radar based in Japan detects the launch, cueing missile defenses aboard Japanese and U.S. ships. The U.S.S. Stetham, an Arleigh Burke-class destroyer equipped with Aegis phased-array radars, fires its SM-3 missiles, which hit and shatter the KN-08 warhead as it begins its final descent. The successful intercept is immediately touted internationally as a victory, but, now desperate for tactical advantage that will allow it to preserve its nuclear and missile programs, the North Korean leadership orders an assault on South Korean patrol vessels and military fortifications built after the 2010 shelling incident.

The regime feels safe in striking out along the maritime boundary because the two sides have repeatedly skirmished in the area in the past 15 years. But President Park, determined to show backbone, dispatches on-alert F-15K fighter aircraft armed with AGM-84E SLAM-Expanded Response air-to-ground missiles to destroy the North Korean installations responsible for the latest assault. For good measure, they also bomb a North Korean mini-submarine pier as belated payback for the sinking of Cheonan. North Korean soldiers and military officers are killed in the attack. Pyongyang vows a merciless response and launches a risky salvo of rockets into downtown Seoul, in hope of shocking the Blue House into seeking an immediate cessation of fighting. But far from ending the tit-for-tat attacks, North Korean actions have now triggered the Second Korean War.

U.S. and ROK Combined Forces Command implements a pre-arranged plan -- perhaps using submarine-launched Tomahawk cruise missiles and Massive Ordnance Penetrator bombs dropped from a B-2 -- to eliminate North Korea's two major missile launch facilities: Tonghae in the northeast and Sohae in the northwest, both of which are fairly close to the Chinese border. North Korea responds with more rockets and Scud missiles, accompanied by North Korean Central News announcements suggesting that they could be armed with biological agents. China, seeking to restrain all sides, pours troops and materiel across the border to protect its interests and instigates a secret plan to replace Kim Jong Un with a senior general who understands the North's total dependence on its only ally. The resulting confusion leads to a belief that North Korea, and not just the Kim regime, is collapsing. Meanwhile, the United States quietly embarks on a secret mission to secure North Korea's nuclear weapons.

In the best case scenario, at this point, an international conference would be convened that would ovesee regime change and perhaps even start a unification process with the South.

Worst case? A terribly weakened North fights on and tens of thousands of people die.

Cronin believes war is more likely to start as a result of miscalculation or accident rather than deliberate design. This may be true, but there will be few who care if the smoke clears and the peninninsula is in ruins.