In a telephone call on Sunday, Trump's national security adviser, HR McMaster, reassured his South Korean counterpart, Kim Kwan-jin, that the US alliance with South Korea was its top priority in the Asia-Pacific region, the South's presidential office said.
The conversation followed another North Korean missile test-launch on Saturday which Washington and Seoul said was unsuccessful, but which drew widespread international condemnation.
Trump, asked about his message to North Korea after the latest missile test, told reporters: "You'll soon find out", but did not elaborate on what the US response would be.
Political commentator Jung-sik Seo analyses.
