South Korea's new liberal President Moon Jae-in promised to seek a parliamentary review of a controversial U.S. anti-missile defense system. If the vote were held today, the deployment would likely be endorsed in the legislative body controlled by conservative and moderate politicians.

More importantly, pushing for that motion would strain Moon's already fraught relations with the opposition, whose cooperation is essential on a more urgent policy goal: creating hundreds of thousands of jobs in a country where youth unemployment is near an all-time high.

Despite the election of the first liberal president in South Korea after nine years of conservative rule, sweeping policy changes on the left are almost untenable in the divided National Assembly, where Moon's Democratic Party holds only 40 percent of the 299 seats.