STORY: Israel on Wednesday began heavy airstrikes on the historic city of Baalbek in Lebanon as U.S. mediators work on a proposal to halt hostilities between Israel and Lebanese armed group Hezbollah.

That's according to two sources who spoke to Reuters that say it would start with a 60-day ceasefire.

"We support their right to go after a legitimate Hezbollah targets. But in doing so, it is critical that they do so in a way that does not threaten the lives of civilians...."

Later on Wednesday State Department spokesperson Matthew Miller commented on Israel's latest actions.

"...we have made clear that the campaign, they are conducting in Lebanon should not, cannot, must not look like the campaign that they (Israel) have conducted in Gaza. We do ultimately want to see a ceasefire. We want to see a diplomatic resolution that allows civilians both in Lebanon and Israel return to their homes."

The sources Reuters spoke to also say a possible two-month ceasefire period would be used to finalize full implementation of UN Security Council Resolution 1701.

It was adopted to try and end an earlier, 2006 war between Israel and Hezbollah, and to help keep southern Lebanon free of weapons or forces outside control of Lebanon's government.

However, it was never fully enforced and has sparked friction with Hezbollah as the group effectively controls that area.

Lebanon's prime minister expressed hope that a ceasefire deal with Israel would be announced within days as Israel's public broadcaster published what it said was a draft agreement of a truce.

The effort comes as Naim Qassem - Hezbollah's new leader - said in his first speech that the Iran-backed group would agree to a ceasefire within certain parameters if Israel wanted to stop the war, but added that Israel had so far not agreed to any proposal that could be discussed.

The latest ceasefire efforts come as Israel's operation against Hezbollah in Lebanon continues to expand.

It also comes days before the U.S. presidential election and in parallel with a similar diplomatic drive on Gaza.