Escalation could lead to nuclear war

We should take every reasonable measure to proactively minimize the risk of a nuclear conflict in Korea.

In diplomacy, we should forsake the goal of North Korean denuclearization in favor of probing North Korea's interest in negotiating an arms control arrangement (which would tacitly permit them to retain at least some nuclear weapons for the foreseeable future).
On sanctions, the current strategy of seeking Chinese pressure on North Korea is unhelpful; either China will not impose excessively tough restrictions on North Korea, or they will and it could cause North Korea to precipitate a crisis as a way to alleviate them. We should maintain sanctions for the purpose of censure, not coercion.
On defense, the United States should avoid actions that might inadvertently trigger North Korean nuclear use. Actions prone to miscalculation include: preventive attacks on North Korean nuclear facilities or critical infrastructure; deployments of U.S. nuclear-capable bombers to South Korea; and large-scale troop movements flowing from around the region into South Korea. North Korea could conclude from any of these moves that we seek to imminently decapitate the regime or invade, forcing it into a "use or lose" situation with its nuclear weapons.

Bottom line: Increasing the diplomatic, sanctions or military pressure too much too quickly, may bring on the world's first nuclear war.

Other voices:

Jim Walsh, Senior Research Associate at MIT's Security Studies Program: Negotiate or else

James Poulos, foreign policy author, contributing editor at American Affairs: Wage cyberwar on North Korea's infrastructure
Wendy R. Sherman, former undersecretary of State for political affairs: Full-court diplomacy (even secret talks with North Korea)
Kurt Campbell, former assistant secretary of State for east Asian and Pacific affairs: A Trump Nixon-to-China moment in North Korea