Trump's suggestion that he may pull back support for South Korea and suspend joint military drills is bad news for a long-standing US ally.

• Trump has floated suspending military exercises with South Korea, pointing to his relationship with Kim Jong-un.
• South Korea has been one of America's most reliable allies for decades, which makes the shift hard to explain.
• Kim is a brutal dictator, and warming to him at Seoul's expense sends a dangerous signal across the region.
• Trump's first-term summit already handed Kim a prize no North Korean leader had ever received — a face-to-face meeting with a US president.
• North Korea gave up nothing in return: no change on its nuclear program, no change toward South Korea.

Outlook: Another round of personal diplomacy with Kim looks likely, and South Korea has reason to worry it will again come away with less security and no concessions from the North.