Israel struck Lebanon with heavy artillery and airstrikes on Saturday after intercepting cross-border attacks, in a move that could embroil the country in a “new war” after months of relative calm.

The Israeli army said three rockets were fired from Lebanon into northern Israel, marking the heaviest exchange of fire between the two countries since the November ceasefire was struck with the Iran-backed militant group Hezbollah to pause a year-long war.

The projectiles set off air-raid sirens in Metula, a small community on the border between Israel and Lebanon.

A Hezbollah official told The Associated Press on Saturday that it was not responsible for the attack, calling it “primitive”.

Eyal Zamir, the Israeli armed forces chief, warned the military would “respond severely”, reinforcing that “Lebanon bears responsibility for unholding the [ceasefire] agreement”.