U.S. Secretary of State Antony Blinken says Seoul, Washington and Tokyo are "united" in dealing with the challenges posed by North Korea.
In a briefing Monday, Blinken said provocations do "nothing to shake the resolve" of the three countries along with other allies and partners to diminish the threat by approaching it from a "position of strength".
The U.S. Ambassador to the UN said Washington is looking at "additional actions" that the UN might take to respond to the North's recent missile tests.
The UN Security Council is expected to hold closed-door meeting on the issue soon.