What could spark a major conflict on the world's most sensitive front line, and just how devastating would it be? Alarm about North Korea has spiked. It claims to have successfully test-launched an intercontinental ballistic missile that could hit Alaska. Some experts estimate that North Korea is now 18 to 36 months away from launching a missile able to reach Los Angeles. President Trump has threatened to "totally destroy" the country, in an exchange of increasingly belligerent messages from both sides. Neal Razzell takes a look at the two sides' war plans and asks: what would war with North Korea look like? Producer: Sarah Shebbeare.