In 1967, when Nasser was dick-swinging around the Middle East, there was a UN force stationed in Sinai that had been there since Suez to protect international waterways.
Nasser ordered them out and the UN Secretary General meekly complied. With them out of the way Nasser closed the Straits of Tiran to international shipping. Israel said that would be a causus belli and they acted on that.
That led to the Six Day War, which left the West Bank & Gaza in Israeli hands. Had the UN force stayed put, it's doubtful the war would've happened and we wouldn't be where we are today.
The UN force in Lebanon was supposed to ensure that Hezbollah met the terms of the 2006 ceasefire and remained north of the Litani river. They conspicuously failed to do that, which is why we're where we are now in Lebanon.
So you could maybe understand why Israel has no faith in the UN.
On a different tangent,
The first attack post 7 October by Hezbollah was on 8th October. The strike was on Shebaa Farm that comprised of old shells and a threat statement that if Israel continues to wage war on Gaza instead of a ceasefire, them Hezbollah will continue to strike Shebaa Farm. No one was harmed.
Shebaa farm is not Israel territory. It is an Israel OCCUPIED territory which Israel rather provide ownership to Syria. Syria however identifies the Shebaa area as Lebanon territory.
Hence, did Hezbollah violate Israel-Lebanon Peace Agreement? Not really, Because it was not cross-border attack.
In retaliation however, Israel identifies it as an attack ON Israel territory, even when Israel itself identifies it as Syrian ‘territory’. Thus, using the arc that Hezbollah did attack on Israel territory, Israel attacked Southern Lebanon. Yes, Lebanon’s real territory. The attack of shells and drone was on civilian area, and 2 Lebanese children were wounded from glass and debris. This cross-border attack identifies Israel as the first contravenor of Israel-Lebanon Peace Agreement.
Days thereafter in October, Hezbollah still attacked on Israel OCCUPIED territory as threats to demand for Gaza ceasefire.
It was not until Israel did attack Lebanese people near the Metula area border (Lebanon-Israel border) that Hezbollah retaliated after in Israel territory.
Hence, a few days after the Metula event, Hezbollah fired an antitank missile near the border BUT in Israel territory. The antitank attack was the first strike from Hezbollah cross territory to actual Israel territory. The antitank missile killed 1 Israel soldier.
Then the tit for tat attacks escalate to the current state.
Israel has been attacking Southern Lebanon and deep Lebanon with air attacks and missiles, killing numerous civilians, which Israel identifies as ‘collateral’, ‘proportionality’ and ‘human shields’. Israel considers that in times of war, civilians will die. Currently, more than 2000 Lebanese have been killed, including 127 children and 261 women.
In contrast, The latest Hezbollah air attack, which was 8 hours ago, used drones covertly flying over any Israel civilian compounds to sneak all the way close to the Israel military base, and conducted precision attack. The attack (based on latest update) killed 7 and wounded 67 (in another figure on wounded, up to 170 wounded). All soldiers.
In a nutshell, Israel emphasises that civilian collateral deaths is unavoidable even with precision munition and intelligence. Hezbollah’s of what they first declared as their ‘uncoventional retaliation’ several days ago, has targeted soldiers.