Hassan Nasrallah, Hezbollah's leader, has warned of a boundless war if Israel invades Lebanon, threatening Cyprus and Israel’s Mediterranean gas fields amid escalating tensions and military preparations.

Hassan Nasrallah, the leader of the Shia paramilitary group, has warned of a battle "without rules or ceilings" if Israeli forces launch an invasion in Lebanon, amid numerous rumors and declarations that Israel and Hezbollah are on the verge of a full-scale conflict.

The previous day,...