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.

The ceasefire had been expected to bring a swift end to weeks of escalating clashes triggered by the mass shooting of tourists last month that India blames on Pakistan.

U.S. President Donald Trump said on Saturday that India and Pakistan had agreed to a "full and immediate ceasefire" after a fourth day of strikes and counter-strikes against each other's military installations.