The truce came after several days of the countries’ most expansive fighting in decades. One Indian official said the country would “deal strongly” with any violations.

India’s missile and bomb strikes on targets in Pakistan and Pakistani-controlled Kashmir have prompted multiple attacks in retaliation between the nuclear-armed neighbors to the point that some are now calling it a de facto war.

The sudden announcement of a U.S.-brokered ceasefire followed four days of steady escalation between India and Pakistan and mixed signals from Washington.