The situation on the Korean peninsula continues to escalate, with the latest being North Korea's threat to attack US and South Korean warships if either country attempts to search North Korean vessels as part of the Proliferation Security Initiative (the PSI is one of President Bush's biggest successes, as it created a global network of inspections and interdictions aimed at preventing transfers of nuclear technology and materiel).
In the face of North Korea's insults, threats, and saber rattling, the US needs to respond forcefully and unambigiously: both the US and South Korea will act to enforce international law, and any attack on South Korea warships or other assets will be met in kind. The US has far too much at stake here to back down in the face of a threat that is, I believe, more bluster than anything: North Korea will lose any military engagement between it and the United States and even losing a small exchange will seriously compromise the stability of a regime that depends on the full and unquestioning support of the military. While the US has few good options, North Korea simply has none. Backing down here will allow North Korea to proliferate internally as well as to continue aiding other countries, such as Syria, to do so as well. Keeping North Korea in check is critical for maintaining stability in Asia, and the US simply cannot allow North Korea to willfully defy international law and will.
This is certainly shaping up to be President Obama's first serious test. Obama needs to reassure American allies and make it clear to both Russia and China that the US will not permit North Korea to proliferate in this manner, to defy international law and will, or to attack South Korea in any way. Despite its often-times bizarre behavior, North Korea has always behaved rationally; it's hard to see what North Korea stands to gain by going to war with either South Korea or the US. Rather, North Korea is counting on the international community to once again fail to back up its words with strong action. Obama must be prepared to send American soliders, sailors, and airmen into combat, but being ready to do so makes it all the more likely that he will not have to do so.