Israel ramped up its offensive against Hezbollah in Lebanon on Wednesday, further eroding an already tenuous cease-fire and raising fears of a return to full-scale war.

The Israeli military said in the wake of increased Hezbollah drone attacks it had struck more than 150 targets associated with the militant group in the past day and had issued evacuation warnings for Nabatieh and Tyre, two of the largest cities in the country’s south.

The conflict in Lebanon has intensified in recent days, complicating efforts by the United States and Iran to reach their own peace deal. On Tuesday, Israeli strikes killed at least 31 people, including four children, according to the Lebanese health ministry.

Hezbollah has shown little sign of backing down. On Wednesday, the Iran-backed group kept up drone and rocket attacks against Israeli troops in southern Lebanon and continued to fire across the border into Israel.

Hezbollah said on Wednesday that its fighters were in close-range combat with Israeli forces in Zawtar al-Sharqiyah, a town that is about six miles from the Israeli border and just north of the Litani River. The clashes signaled that Israel’s forces were advancing beyond what it calls the “forward defense line,” an area extending several miles into southern Lebanon that Israel has occupied since its March invasion.

Despite a nominal cease-fire that took effect in April, Hezbollah and Israel have continued to trade attacks, deepening fears that the truce could collapse altogether. The recent escalation has come just as diplomatic efforts to secure an agreement between the United States and Iran appeared to be inching forward.

Facing pressure from Israeli hard-liners, Mr. Netanyahu said on Tuesday that the country’s military was “deepening its operation” inside Lebanon, adding to uncertainty over whether its war with Hezbollah would be part of any overall U.S.-Iran deal.

While Iranian officials have previously told The New York Times that a peace agreement would end fighting on all fronts, including Lebanon, Mr. Netanyahu has suggested that Israel would still be able to defend itself against threats from Hezbollah there, saying President Trump had affirmed that.

In recent weeks, Lebanese and Israeli government officials have held rare direct talks in Washington aimed at brokering a longer-term settlement to end the fighting. Military officials from both sides are scheduled to meet at the Pentagon on Friday under U.S. supervision, with a separate round of political talks set for next week.

But Hezbollah is not a party to the talks, which it has denounced, vowing instead to fight on until Israel stops its attacks and withdraws from Lebanon.