India and Pakistan agreed to an immediate ceasefire on Saturday, unexpectedly halting the worst fighting in decades between the nuclear-armed neighbors, just when their tit-for-tat strikes appeared to be spiraling out of control.

A fragile ceasefire was holding between India and Pakistan on Sunday, after hours of overnight fighting between the nuclear-armed neighbours, as U.S. President Donald Trump said he will work to provide a solution regarding Kashmir.

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.