Sheikh Hassan Nasrallah warns the fall of the Assad regime wold plunge the Middle East into a "dark period."
Israel said it returned fire at the source and scored a "direct hit."
Confidential report from the International Atomic Energy Agency this week indicated Iran upgraded uranium enrichment facilities and steps toward plutonium production.
Israel eyes possible knock-on wars with Hezbollah, Iran; fears "strategic looting" of Syria's weaponry.
Preparing instead to resume campaign of seeking membership in key international organizations as soon as next month.
Tehran's holding of medium-enriched uranium gas is closely watched in the West.
Israel said Syrian gunfire hit Israeli patrol, prompting troops to fire back.
Secretary of State John Kerry will press case for talks between rebels and President Bashar Assad's regime.
Saeb Erekat tells the U.N. he has no preconditions for returning to the table as the U.S. secretary of state works to revive long-stalled talks.
Israel says a French TV report in 2000 that claimed Israeli forces killed a Palestinian boy is misleading.