The Israel Defense Forces announced that a fourth division joined its ground operation in southern Lebanon on Monday.

The 146th Division "began limited, localized, targeted operational activities against Hezbollah terror targets and infrastructure in southwestern Lebanon," the IDF said. The 146th was previously deployed along Israel's northwestern border with Lebanon in a defensive role, it said.

The IDF said the 146th Division is the first reserve division to be deployed into southern Lebanon. Its troops will be supported by the 213th Artillery Brigade and other units, the IDF said.

The 146th joins the 91st Galilee Division, 98th Paratroopers Division and 36th Division which are already in action in southern Lebanon.

-ABC News' Jordana Miller

The Israel Defense Forces said they struck more than 120 Hezbollah targets in southern Lebanon on Monday within an hour.

The airstrikes followed evacuation orders earlier Monday.

Over the past 48 hours, 190 airstrikes were recorded throughout Lebanon, primally in the south, according to the Lebanese Security Council. Forty-seven people were killed and another 207 injured, according to the Lebanese Ministry of Public Health.

Approximately 190 projectiles were fired by Hezbollah from Lebanon into Israeli territory on Monday, according to the IDF.

Vice President Kamala Harris and second gentleman Doug Emhoff marked the first anniversary of the Oct. 7 attack by planting a pomegranate tree -- a symbol of hope and righteousness in Judaism -- at the vice president's residence.

Harris said the tree will "remind future vice presidents of the United States, their families and all who pass through these grounds, not only of the horror of Oct. 7, but the strength and the endurance of the Jewish people."

The vice president underscored her pledge to make sure Israel has what it needs to defend itself.

Harris also said the world must "work to relieve the immense suffering of innocent Palestinians in Gaza who have experienced so much pain and loss over the year."

Emhoff, the first Jewish spouse of a president or a vice president, also spoke about the "incredibly challenging day for Jews."

"We are still hurting, and today feels just as raw as it did one year ago," he said. "What happened on Oct. 7 is seared into our souls."

-ABC News' Molly Nagle

Israeli incursions into Lebanon continue to be limited, State Department spokesperson Matthew Miller said Monday, noting that this assessment does not "offer any kind of forecast about what's going to happen."

Miller asserted that U.S. officials were still engaged in talks about "what the path forward ought to look like" with a variety of partners in the Middle East.

"Just because we don't make the details of those conversations public, which we are not at this point, doesn't mean that we are not actively engaged in them," he said.

Similarly, he said Israel's campaign in Lebanon hadn't impacted the administration’s drive to secure a cease-fire in Gaza and characterized Hamas as the main hurdle that has been "unwilling to engage in a meaningful way with the mediators.”

-ABC News' Shannon K. Kingston