Israeli strikes killed at least nine people in southern Lebanon, Lebanese authorities said Monday, the deadliest day since a ceasefire brokered by the United States and France came into effect last week.

Israel hits Lebanon with its largest wave of airstrikes since agreeing to a ceasefire with Hezbollah, as both sides accuse each other of violations.

Both sides have accused each other of violating the deal; Hezbollah fired into Israel for the first time since the truce took effect, and Israel responded with airstrikes.

As tit-for-tat strikes strain a ceasefire between Israel and Hezbollah less than a week since it went into effect, Israel’s defense minister on Tuesday threatened to directly target the Lebanese state should the agreement fall apart.

The Israeli military says Hezbollah has fired into a disputed border zone, its first attack since a ceasefire took hold last week. It comes after Hezbollah accused Israel of violating the truce with airstrikes and shelling in Lebanon.

The Israeli military said on Monday it struck dozens of targets throughout Lebanon, shortly after Hezbollah accused Israel of violating a ceasefire agreement and fired missiles on an Israeli military position in the disputed Shebaa Farms area.

The rebel offensive in Syria started after Israel and Hezbollah agreed to a cease-fire in Lebanon, where conflict has weakened key backers of Syria’s government.

Israel issued a warning at Lebanon that it will not long distinguish between Beirut and Hezbollah should the cease-fire between Jerusalem and the terrorist group collapse following an exchange of strikes.