TEL AVIV, Israel — The Israeli military is preparing for a possible ground operation in Lebanon, the Israeli army chief said Wednesday as Hezbollah fired dozens of rockets into Israel and a missile aimed at Tel Aviv that was the militant group’s deepest strike yet.

Addressing troops on the northern border, Chief of Staff Lt. Gen. Herzi Halevi said the latest airstrikes were designed to “prepare the ground for your possible entry and to continue degrading Hezbollah.”

In an apparent reference to the missile fired at Tel Aviv, he told troops: “Today, Hezbollah expanded its range of fire, and later today, they will receive a very strong response. Prepare yourselves.”

It was not clear whether Halevi was referring to a ground operation, airstrikes or some other form of retaliation against Hezbollah, which is Lebanon’s strongest political force and, with backing from Iran, is widely considered the top paramilitary group in the Arab world.

The Israeli military has said in recent days it had no immediate plans for a ground invasion. Halevi’s comments were the strongest yet suggesting troops could move in.

With hostilities intensifying, the Israeli military said Wednesday it would activate two reserve brigades for missions in the north — another sign that Israel plans tougher action.

In the southern Israeli city of Eilat, a building at the port was struck by a drone, an attack that injured two people and was claimed by an umbrella group for Iranian-backed militias in Iraq. A second drone was intercepted, the Israeli military said.

The army said the drones were identified “approaching from the East.”

Tensions between Israel and Hezbollah have steadily escalated since war broke out 11 months ago between Israel and Hamas, another Iran-backed militant group. Hezbollah has been firing rockets, missiles and drones into northern Israel in solidarity with Palestinians in Gaza and Hamas. Israel has responded with increasingly heavy airstrikes and the targeted killing of Hezbollah commanders while threatening a wider operation.

Nearly a year of fighting had already displaced tens of thousands of people on both sides of the border before the recent escalation.

Israel has vowed to do whatever it takes to ensure its citizens can return to their homes in the north, while Hezbollah has said it will keep up its rocket attacks until there is a cease-fire in Gaza, something that appears increasingly remote.

To allow displaced Israelis to return to their homes, “we are preparing the process of a maneuver,” Halevi said.

U.S. Secretary of State Antony Blinken urged Israel and Hezbollah to step back, saying all-out war would be disastrous for the region and its people.

In New York for the annual U.N. General Assembly, Blinken said the U.S. was working with other partners on a temporary cease-fire plan to reduce tensions and allow Israelis and Lebanese to return to their homes in border areas.

U.S. officials say they are floating ideas but have not been specific.

Lebanon’s health minister said more than 50 people were killed Wednesday in the continuing Israeli strikes, raising the death toll from the past three days to 615, with more than 2,000 wounded.

This week has been the deadliest in Lebanon since the bruising 2006 monthlong war between Israel and Hezbollah.

Hezbollah said it fired a Qader 1 ballistic missile targeting the headquarters of Israel’s Mossad intelligence agency, which it blames for a recent string of targeted killings of its top commanders and for an attack last week in which explosives hidden in pagers and walkie-talkies killed dozens of people and wounded thousands, including many Hezbollah members.

Israeli military officials said they intercepted a surface-to-surface missile that set off air-raid sirens in Tel Aviv and across central Israel. There were no reports of casualties or damage. The military said it struck the launch site in southern Lebanon.

Israeli military spokesman Lt. Col. Nadav Shoshani said the missile fired Wednesday had a “heavy warhead” but declined to elaborate or confirm it was the type described by Hezbollah. He dismissed Hezbollah’s claim of targeting the Mossad headquarters just north of Tel Aviv as “psychological warfare.”

The Iranian-made Qader is a medium-range surface-to-surface ballistic missile that can carry an explosive payload of up to 1,760 pounds, according to the Washington-based Center for Strategic and International Studies. Iranian officials have described the liquid-fueled missile as having a range of 1,240 miles.

Israel said Wednesday that its air force had struck some 280 Hezbollah targets across Lebanon by early afternoon, including launchers used to fire rockets on the northern Israeli cities of Safed and Nahariya.

Fleeing families have flocked to Beirut and the coastal city of Sidon, sleeping in schools turned into shelters, as well as in cars, parks and along the beach. Some sought to leave the country, causing a traffic jam at the border with Syria.

The United Nations said more than 90,000 people have been displaced by five days of Israeli strikes. In all, 200,000 people have been displaced in Lebanon since Hezbollah began firing rockets into northern Israel nearly a year ago, drawing Israeli retaliation, according to the U.N. Office for the Coordination of Humanitarian Affairs.

Hezbollah’s latest strikes included dozens of rockets fired Wednesday into northern Israel, the military said.