South Korea warned North Korea on Tuesday of “enormous retaliation” if it took more aggressive steps after Pyongyang fired scores of artillery shells at a South Korean island in one of the heaviest attacks on its neighbor since the Korean War ended in 1953.

The South fired back after Tuesday’s attack and sent fighter jets to the area, close to a disputed maritime border on the west of the divided Korean peninsula and the scene of deadly clashes between the two rivals in the past.

South Korea was conducting military drills in the area at the time, but said it had not been firing at the North. Pyongyang blamed Seoul for starting the fight, which killed two South Korean soldiers and wounded 17, others along with three civilians, and razed scores of houses.

“Houses and mountains are on fire and people are evacuating,” a witness on the island told YTN Television.

Deadly game

Experts say North Korea’s Kim has for decades played a carefully calibrated game of provocation to squeeze concessions from the international community and impress his own military.