US Defense Secretary Lloyd Austin had spoken with Israeli counterpart Yoav Gallant about Israel's defense against attacks by the Lebanese group, Pentagon spokesman Major General Pat Ryder said.

"Secretary Austin reaffirmed the United States' ironclad commitment to Israel's defense against any attacks by Iran and its regional partners and proxies," Ryder said in a statement.

A Pentagon spokesperson added in a separate statement that the United States has "been very clear" that it "is postured to support the defense of Israel."

Gallant announced a 48-hour nationwide state of emergency in Israel from 06:00 am (0300 GMT) Sunday after the military launched what it called pre-emptive strikes in Lebanon.

The Israeli defense ministry said Gallant had briefed Austin on the situation.

"We have conducted precise strikes in Lebanon in order to thwart an imminent threat against the citizens of Israel," Gallant told Austin, according to a statement.

US National Security Council spokesman Sean Savett said "senior US officials have been communicating continuously with their Israeli counterparts" at the direction of President Joe Biden, who was "closely monitoring events in Israel and Lebanon."

"We will keep supporting Israel's right to defend itself, and we will keep working for regional stability," Savett said in a statement.

Hezbollah issued a statement Sunday announcing large-scale drone and rocket launches targeting deep into Israeli territory in retaliation for the death of its military commander in an Israeli strike last month.