New Year's traditions differ across the Pacific. Americans break out bottles of champagne and wake up with headaches and fuzzy memories. Koreans try to maintain sobriety in order to bow to family elders on Jan. 1 and receive blessings for the peace, prosperity and health of their entire clan. Such cultural differences, as superficial as they might seem, might offer a lesson in foreign policy.

On New Year's Day, North Korean leader Kim Jung Un addressed a very large political "family," telling members that 2019 was "full of hope" and that all Koreans "should make greater strides in our efforts to boost inter-Korean relations, achieve peace and prosperity and reunify the country." South Korean citizens, for the first time able to watch his annual address on television simultaneously with their northern kin, received a similarly optimistic message from their own president, Moon Jae-in, who promised in his national greeting: "I will make sure the peace will be irreversible."

The coming year indeed promises continued warming of relations between the two Koreas and efforts to pave their own paths toward peaceful cooperation while U.S. President Donald Trump tries to denuclearize Pyongyang on his own terms. However, the 2-1 lineup bodes ill for the Washington-Seoul alliance — currently under pressure over the expiry of the cost-sharing deal for the U.S. troops stationed on the peninsula and concerns over a growing gap in North Korea policy — unless the Trump administration puts other items on the negotiating table. The White House also needs to work with Seoul on reconciliation and confidence-building measures in tandem with denuclearization efforts.