JERUSALEM — Iran launched almost 200 missiles at Israel on Tuesday evening, causing scattered damage and fires from falling shrapnel, but Israeli authorities said there were no injuries. An Israeli security official said most of the missiles were intercepted, though some managed to land.

Israeli officials said Iran would pay a price for the strike.

The missile attack came after Israel said ground troops crossed into Lebanon overnight, launching what the military described as a limited operation to root out Hezbollah fighters and infrastructure.

Hezbollah, meanwhile, said it saw no sign of Israeli forces and that its troops were ready to confront them.

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Israel said the incursion would be focused on the narrow strip of land just across the border. But it also issued evacuation warnings covering a wider swath of Lebanon, raising fears that a large-scale ground invasion was soon to come.

In recent days, a wave of Israeli airstrikes has killed Hezbollah leader Hassan Nasrallah and several of his top commanders, while driving hundreds of thousands of Lebanese from their homes. Israel says a ground operation is now necessary to return tens of thousands of displaced Israelis to their homes in the north, pummeled by continuous rocket fire from Hezbollah since Oct. 8.

Here’s what we know:

Why Did Iran Launch Missiles Toward Israel?

Israel’s military said it identified 180 missiles launched from Iran shortly after 7:30 p.m. Sirens blared across the country, and Israelis were ordered to stay in protected areas. An Israeli security official said that in cooperation with the United States, the Israeli Air Force intercepted many of the missiles, though there some direct hits damaging buildings and igniting some fires.

Iran said the missiles were in response to the killing of Hezbollah leader Hassan Nasrallah and Revolutionary Guard Gen. Abbas Nilforushan, both killed in an Israeli airstrike last week in Beirut. It also mentioned Ismail Haniyeh, a top leader in Hamas who was assassinated in Tehran in a suspected Israeli attack in July. It warned this attack represented only a “first wave,” without elaborating.

In April, Iran launched more than 300 drones, ballistic missiles and cruise missiles at Israel. Most were intercepted outside of Israel. One girl was injured from falling shrapnel.

Israel vowed to respond, pushing the two archenemies closer toward direct confrontation and the region closer toward a broader war.

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Did Israeli Troops Enter Lebanon?

The military says that Israeli troops entered Lebanon late Monday, though it was not clear whether they remained inside or were moving in and out of the country.

In a surprise announcement, Israel said Tuesday that its ground forces have been operating covertly in Lebanon for the last year, carrying out dozens of small ground operations. Rear Adm. Daniel Hagari, the army’s spokesman, said the current raid is an expansion of these activities.

The Lebanese army and UNIFIL, a U.N. peacekeeping force stationed in southern Lebanon, have not confirmed that Israeli troops crossed the border, although UNIFIL said it was notified that they were going to.

How Far Into Lebanon Are Israeli Ground Troops?

A military official, speaking on condition of anonymity under briefing guidelines, said Israeli ground troops were “within walking distance” of the border, targeting the small Lebanese villages hundreds of meters (yards) from Israeli territory.

The military says Hezbollah militants remain in the area, despite heavy Israeli bombardment over the past few weeks. It says they are using the areas to launch attacks on Israel and to store weapons.

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Have There Been Clashes Between Hezbollah and Israeli Troops?

There were no signs of ground combat in southern Lebanon, and the Israeli official said there had been no clashes with Hezbollah.

Meanwhile, cross-border fire continued. Hezbollah said it had targeted groups of soldiers in several Israeli border areas with artillery shelling and rockets. Israel said no soldiers were injured. At the same time, Israeli artillery units pummeled targets in southern Lebanon and the sounds of airstrikes were heard throughout Beirut.

Hezbollah fired a rare volley of rockets toward central Israel on Tuesday, injuring one man, Israeli paramedics said.

How Extensive Is the Planned Operation?

Israel has not given a timetable for how long the incursion will last and has declined to specify how far troops will go.

The military official said that marching to Beirut, as Israel did in its 1982 invasion of Lebanon, is “not on the table.” At the time, the Israeli invasion was also pitched as a limited incursion to push the Palestine Liberation Organization back.

He added that the operation in its current stages does not mirror Israel’s ground incursions in Gaza, where the military entered cities with heavy manpower, artillery and tanks.

That could change, depending on whether Israel’s government decides to launch a more extensive ground operation. Large numbers of forces, including scores of tanks, have massed along the border in recent days.

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Troops that entered Lebanon are from the 98th division, the military said. The division is responsible for some of the heaviest fighting inside Gaza and includes elite units specializing in attacks behind enemy lines.

Meanwhile, Israel is expanding its evacuation warnings in southern Lebanon, sending hundreds of thousands of Lebanese fleeing from the south.

On Tuesday, the Israeli military’s Arabic-language spokesperson asked residents living in villages north of a U.N.-declared buffer zone to flee. Under a U.N. resolution that ended the 2006 war, the zone was supposed to be controlled by a U.N. peacekeeping force and the Lebanese military.