The Trump Administration insists that it will prevent North Korea from deploying a nuclear-armed ICBM that could target the continental United States, or preempt an imminent launch of a missile against the United States or the territory of a U.S. ally.
Any military actions against North Korean territory would necessitate the employment of overwhelming force that would be certain to trigger major retaliation against South Korea and Japan, and possibly against U.S. territory.
The U.S. could try to intercept any future North Korean missile tests that approach U.S. territory. Secretary of Defense Mattis has already warned Pyongyang that the U.S. would seek to shoot down any missile landing close to Guam, thereby denying North Korea the means to reach U.S. soil. It would be by far the least destructive military option, and (if successful) might enable avoidance of a horrific armed conflict on the peninsula, and beyond.
Bottom line: However, if anyone is seeking low cost, low risk military options, Korea is the wrong place to look.