If Israel discovers that Hezbollah is rearming, then they are to file a complaint with the UN:

UN Secretary General Kofi Annan views the Israel Defense Forces’ commando operation near Baalbek over the weekend as a violation of the cease-fire agreement, UN envoy Terje Roed-Larsen told Foreign Minister Tzipi Livni during their meeting in Jerusalem Monday. “If you discovered arms smuggling, you could have complained through diplomatic channels,” Larsen told Livni.
“We will consider that route as well,” Livni replied with a smile.

Then what? Will the UN stop Hezbollah from rearming? Ha! As we have seen over and over and over again just this last week, that’s not going to happen.
(Link via little green footballs)