Tensions on the Korean Peninsula have spiked this year, as North Korea has conducted an unprecedented number of missile tests and repeatedly violated a landmark military agreement signed with the South in 2018.

But while Washington is always concerned with Pyongyang upping the ante, history shows it’s also been quietly uneasy at times about how ally South Korea might react to escalation and drag the U.S. into a conflict.

According to Article III of the 1953 Mutual Defense Treaty, the U.S. would only be obliged to come to South Korea’s defense in the