South Korea has accused North Korea of sinking one of their warships. North Korea has taken two steps forward and is making threats against the South and everyone else. The US has jumped on board and says it will support South Korea. The president has suggested that the US military needs to be prepared for a new international order which includes a belligerant North Korea.
So what happens next? Odds are another round of sanctions against North Korea. That country is already cut off from most of the world and with the exception of shipments from Burma or China, is pretty much on its own. But sanctions and denouncements from the UN are the best expectations.
Now, what is the worse case scenario?
First, the South procedes with sanctions. The North, knowing their have little to lose and all that military might and energy poised on the border, takes a tougher stand. They resume lobbing a few shells at the South, reopen some tunnels and drop more mines and mini subs in the waters between the two countries.
Eventually, someone else gets hurt. The South goes on wartime footing and masses defense forces on the border. The US president, reluctant to up the ante, advises non-essential Americans to consider leaving the country and orders an aircraft carrier from Japan to the coast of South Korea.
South Korea catches an armed group attempting to enter the country through a series of underground tunnels. At the same time, a number of sabotage attempts, some successful, are made on facilities around the South such as power stations, water treatment plants and fuel storage facilities.
The South, begins agressively patroling its borders and a number of skirmishes are reported. The US, unable to deny that resumption of hostilities are possible, prepares two divisions in the US for deployment to the region as well as three more aircraft carriers. Troops in Iraq begin preparations to quickly move to the front if needed.
China enters the scene and declares that any agression by the US towards North Korea will be met with a "harsh and complete response". China begins to mass troops of its own on the border with the North and moves a number of warships to the area. Russia is planning on "watching the situation closely", but is also mobilizing its military in the east just in case.
The US asks the UN for a resolution and for immediate peace talks, but China vetos the motion and instead demands the the US pull out additional troops and ships from the region.
North Korea, enjoying the attention and lack of decisive action, launches a 24 hour attack on the South and pushes several miles across the border before pulling back. There are US service casualties and the president, facing pressure from both sides of the aislie, sends the US Air Force into action to both bomb North Korean positions and achieve air superiority.
Both North Korean and Chinese aircraft respond and there are losses on both sides. With limited resources available to the US due to additional troops and aircraft not yet arriving from the US and the drain on the US military in the Mideast, the president has no choice but to pull back to a defensive position.
The North Koreans and and increasingly antagonistic Chinese military push back and begin a full scale invasion of the South. US forces retreat to Seoul and then further south. The US begins a massive effort to evacuate the thousands of US citizens in South Korea with civilian airliners. When an American Airlines passenger jet is shot down over the China Sea, the US is forced to go to full retaliation.
Cruise missiles and aircraft from the South, Japan and the US begin bombing the North and along the Chinese-Korean border to stem the flow of troops and supplies. The Chinese retaliate against the US fleet and damage and sink several US ships including one aircraft carrier.
The US president warns China that nuclear weapons will be used unless it pulls back to the North Korean borders and China responds by firing a nuclear weapon off its coast at US forces at sea.
In the US panic erupts as millions of Americans rush to grocery and hardware stores in an attempt to prepare for nuclear war. City residents protest in the streets demanding to know where the "bomb shelters" are in the cities. Millions pack their possessions into cars and head to the country emptying grocery stores and gas stations along the way.
In these critical hours, Russia warns both the US and China that if further nuclear weapons are used, they will be forced to unleash their inventory as well in a pre-emptive move. The US president attempts one more gesture at peace by sending the secretary of state to Bejing in an eleventh hour mission of urgency. When that fails, he addresses the public and urges them to remain calm, assist their neighbors and work with their communities. He also imposes some purchase limits on grocery shoppers and gasoline customers which only results in the complete opposite reaction from the public.
That night, shortly after midnight, China launches several nuclear missiles aimed at Japan and the US West Coast. The US, after a period of delay, fires a like number of land based missiles at China which triggers Russia to launch a greater number at both countries.
Within one hour, the world has changed forever.