Israel expanded its ground assault in Lebanon with its broadest incursion into the country in a quarter-century as Hezbollah — Iran’s most powerful regional ally — stepped up attacks on Israel’s north.

According to the Israeli military, Hezbollah fired more than 300 “projectiles” at its soldiers in Lebanon and at northern Israel over the weekend. The latest escalation has shattered a brittle ceasefire declared after the Tehran-backed group attacked Israel in response to its war on Iran, which it launched with the US on Feb. 28.

As part of a military operation that started several days ago, the Israeli Defense Forces said in a statement that they’d crossed the Litani River and are near Shi’ite-majority Nabatieh — one of the biggest cities in south Lebanon — which the IDF describes as a stronghold of Hezbollah.

“I have instructed the IDF to expand the incursion in Lebanon. Our forces have crossed the Litani River and took dominant terrain,” Prime Minister Benjamin Netanyahu said in a statement citing the capture of the Beaufort ridge.

Sunday’s escalation comes against the backdrop of a tense stalemate between Israel’s top ally, the US, and Iran over an agreement that could potentially pave the way for a permanent ceasefire between the long-time foes.