U.S. President Joe Biden will make a high-stakes visit to Israel on Wednesday as it prepares to escalate an offensive against Hamas militants that has set off a humanitarian crisis in Gaza and raised fears of a broader conflict with Iran.

Biden’s visit will mark a significant show of U.S. support for its top Middle East ally after Hamas gunmen killed 1,300 people during a rampage through southern Israeli towns on Oct. 7, the deadliest single day in Israel’s 75-year history, Reuters reported.

Israel has responded by tightening its blockade on Hamas-ruled Gaza, including by restricting the entry of fuel, and bombarding the area with air strikes that have killed thousands of Palestinians and displaced hundreds of thousands more.

U.S. Secretary of State Antony Blinken concluded hours of talks with Israeli Prime Minister Benjamin Netanyahu in Tel Aviv early on Tuesday by saying that Biden would visit Israel.

“The president will hear from Israel what it needs to defend its people as we continue to work with Congress to meet those needs,” Blinken told reporters.

Biden would meet with Netanyahu, reaffirm Washington’s commitment to Israel’s security, and receive a comprehensive brief on its war aims and strategy, Blinken said.

“(The) president will hear from Israel how it will conduct its operations in a way that minimizes civilian casualties and enables humanitarian assistance to flow to civilians in Gaza in a way that does not benefit Hamas,” Blinken added.

Blinken also said he and Netanyahu had agreed to develop a plan to get humanitarian aid to Gaza civilians. He did not provide details.

After visiting Israel, Biden would travel to Jordan to meet King Abdullah, Egyptian President Abdel Fattah al-Sisi and Palestinian Authority President Mahmoud Abbas, U.S. national security spokesperson John Kirby said.

Gaza authorities say more than 2,800 people have been killed in Israeli attacks since Oct. 7, around a quarter of them children, and more than 10,000 wounded are in hospitals desperately short of supplies.

Israeli officials say that in addition to the casualties Hamas inflicted, the Iran-backed group took some 199 hostages into Gaza, Reuters reported.

Khaled Meshaal, a top Hamas leader, said on Monday the group “has what it needs” to free all Palestinians in Israel’s jails, indicating it may try to use the kidnapped Israelis as bargaining chips.

Soon after Meshaal’s remarks, the group’s armed wing separately said the non-Israelis it had taken captive were “guests” who would be released “when circumstances allow”.

Hamas released a video on Monday in which a French-Israeli woman captive was shown having her injured arm treated by an unidentified medical worker. She identified herself as 21-year-old Mia Schem and asked to be returned to her family as quickly as possible.

The Israeli military said it had struck Hamas and Islamic Jihad military targets overnight, including Hamas’ headquarters and a bank used by the group. It said a Hamas military operative was killed in the strikes.

Biden’s trip is a rare and risky choice, showing American backing for Netanyahu as the U.S. tries to avert a broader regional war involving Iran, its Lebanese ally Hezbollah and Syria. It comes as Israel is preparing a ground offensive in Gaza expected to intensify the enclave’s humanitarian crisis.

Iranian Foreign Minister Hossein Amirabdollahian told state TV that Israel would not be allowed to act in Gaza without consequences, warning of “preemptive action” by the “resistance front” in the coming hours.

Iran refers to regional countries and forces opposed to Israel and the United States as a resistance front.

“All options are open and we cannot be indifferent to the war crimes committed against the people of Gaza,” Amirabdollahian said. “The resistance front is capable of waging a long-term war with the enemy.”

Japan, the current president of the Group of 7 developed nations, said it was in the final stages of arranging a call with Iran, Foreign Minister Yoko Kamikawa said, as she announced $10 million in humanitarian aid for Gaza.

Last week, Iran’s Supreme Leader Ayatollah Ali Khamenei said Tehran was not involved in the Hamas attack on Israel, but hailed what he called Israel’s “irreparable” military and intelligence defeat.

In the biggest sign yet that the war could spread to a new front, Israel ordered the evacuation on Monday of 28 villages in a 2-km-deep zone near the Lebanese border.

Netanyahu said Israelis should prepare for a long battle.

“And I have a message for Iran and Hezbollah, don’t test us in the north. Don’t make the same mistake you once made. Because today the price you will pay will be much heavier,” he told the Israeli parliament on Monday.

Diplomatic efforts have concentrated on getting aid into Gaza through the Rafah crossing with Egypt, the sole route that is not controlled by Israel. Cairo said the Rafah crossing was not officially closed but was inoperable due to Israeli strikes on the Gaza side.

On the military front, the U.S. has deployed two aircraft carriers and their supporting ships to the eastern Mediterranean since the attacks on Israel. The ships were meant as a deterrent to ensure the conflict did not spread, U.S. officials said.

The top U.S. general overseeing American forces in the Middle East, Central Command chief Army General Michael “Erik” Kurilla, made an unannounced trip to Israel on Tuesday, saying he hoped to ensure its military has what it needs.

As Israel masses troops on Gaza’s border, it has told more than a million people in the northern half of the enclave to flee to the southern half for their safety, even though Hamas has told them to stay put, Reuters reported.

While tens of thousands have fled south, the United Nations says there is no way to move so many people without causing a humanitarian catastrophe.

The United Nations says a million Gazans have already been driven from their homes. Power is out, sanitary water is scarce and fuel for hospital emergency generators is running low.

Russian President Vladimir Putin told Netanyahu on Monday that Moscow wanted to help prevent a humanitarian disaster. A Russian-drafted U.N. Security Council resolution that would have called for a humanitarian ceasefire failed to get the minimum nine votes needed in the 15-member body on Monday.