Officials from the U.S. and South Korea promised a “unified response” to North Korea’s recent intercontinental ballistic missile (ICBM) and other “escalatory” weapons tests carried out since the start of the year.

The pledge came during a meeting between U.S. Special Representative for the DPRK Sung Kim and his South Korean counterpart Noh Kyu-duk in Washington on Monday, according to the State Department.