The Pentagon said the United States is sending "a few thousand" additional troops to the Middle East to bolster security and prepare to defend Israel if necessary, the Associated Press reported.

The deployment will include squadrons of F-15, F-16, F-22 and A-10 fighter jets and the personnel needed to support them. The squadrons were initially assigned to the Middle East so other fighter jets could rotate, but they will now all remain to augment U.S. air power.

The day before the announcement, President Biden was asked if he would send more troops to the Middle East and replied, “No.”

The deployment comes after Israel killed Hassan Nasrallah and massacred hundreds of Lebanese civilians since Israel dramatically escalated its bombing campaign in Lebanon last week. U.S. support for Israel’s attacks on Lebanon could lead to attacks on U.S. forces in the region, or the United States could intervene directly to defend Israel.

Pentagon spokeswoman Sabrina Singh said the deployment was to “protect US forces,” not to assist with evacuations. Last week, Singh said the US was beefing up its forces in the region “if we need to defend Israel.”

The Pentagon announced Sunday that Defense Secretary Lloyd Austin had ordered an aircraft carrier strike group and an amphibious assault group to remain in the region. The Pentagon also issued a warning to Iran on Sunday, saying Defense Secretary Lloyd Austin “made clear that if Iran or its partners or proxies use this moment to target U.S. personnel or interests in the region, the United States will take all necessary action to defend our people.”

The Israeli military began invading Lebanon early Tuesday morning, marking a major escalation of the offensive against Hezbollah fighters and opening a new front in a year-long war since Israel launched its war on the blockaded Gaza Strip. The incursion follows weeks of heavy Israeli strikes on Hezbollah — including an airstrike that killed the group’s leader, Sayyed Hassan Nasrallah — and seeks to ramp up pressure on the group, which began firing rockets into northern Israel after the Gaza war began. The last time Israel and Hezbollah engaged in ground combat was a month-long war in 2006.

The Israeli occupation army said in a brief statement that it had begun "limited, local and targeted ground raids" against Hezbollah targets in southern Lebanon.

“These targets are located in villages close to the border and pose a direct threat to Israeli communities in northern Israel,” he said. There was no word on how long the operation would take, but the military said soldiers had been training and preparing for the mission in recent months. Israel said it would continue to strike the group until it was safe for Israelis displaced from border communities to return to their homes.

Before the Israeli announcement, US officials said Israel had launched small ground raids inside Lebanon, and Israel had declared three small border villages a "closed military zone," restricting access to them only to military personnel.

There were no reports of direct clashes between Israeli forces and Hezbollah fighters. But throughout the evening, IDF artillery units shelled targets in southern Lebanon and the sound of airstrikes could be heard throughout Beirut.