And why should we believe Hizbullah has no resposibility?

It seems as though the warnings that Iran is going to open a second front against Israel are true.
An unprovoked rocket attack was launched against Israel from Lebanon. Notice this comes from Southern Lebanon, where Hizbullah has full control. Who are Hizbullah's masters? Syria and Iran.

Indirectly this is the Government of Lebanon's fault too. Most people would agree that a Government's responsibilities are to control their borders among other things. But with Hizbullah operating as a state within a state, against all norms of International Law, acts of War are conducted against Israel from Southern Lebanon.

This is why UN Resolution 1559 has not been implemented, and needs to be ASAP.