Japan, U.S. and South Korean military cooperation reached a new milestone last week when the three countries conducted their first-ever trilateral aerial exercise.

The drill is the first substantive product of the agreement reached by the three governments at the Camp David Summit last August. This momentum should continue to allow the three countries to institutionalize progress across a range of endeavors.

Regional adversaries have and will complain. North Korea responded as expected and will likely commit some provocative act to show that it is not intimidated and China will surely object. Our three nations must not be deterred or distracted. Trilateral cooperation is in our national interest and the protests of adversaries is a sign that it is working as intended.