The problem is that South Korean economic measures, US condemnation and even possible action at the UN are unlikely to change the mindset in Pyongyang.
China is the only country with any real leverage over North Korea.
Behind the scenes Beijing is going to be the crucial player if tensions are not to spill out of control.
The weeks ahead are punctuated with opportunities for further tensions - not least a joint US-South Korean anti-submarine exercise.
ATTACKS BLAMED ON NORTH
* Jan 1967 - South Korean warship attacked near border, 39 sailors killed
* Jan 1968 - presidential palace in Seoul stormed, 71 killed
* Oct 1983 - Rangoon hotel used by South Korean president bombed, 21 killed
* Nov 1987 - South Korean airliner bombed, 115 killed
* Mar 2010 - Cheonan warship attacked, 46 sailors killed