Israeli Prime Minister Benjamin Netanyahu vowed on Sunday to fight deeper into Gaza after his troops endured one of the worst days of losses of their ground war, while militant group Islamic Jihad joined talks in Cairo, a sign diplomacy was still alive.

The arrival of a delegation in Cairo headed by Islamic Jihad’s exiled leader Ziad al-Nakhlala followed talks attended by Hamas chief Ismail Haniyeh in recent days. Islamic Jihad, while smaller than Hamas, is also holding hostages in Gaza.

The militant groups have so far said they will not discuss any release of hostages unless Israel ends its war in Gaza, while the Israelis say they are willing to discuss only a temporary pause in fighting.

But neither side has publicly walked away from talks that Washington last week described as “very serious,” even as fighting has intensified throughout the Gaza Strip since a truce collapsed at the start of December.

The Cairo talks would center on “ways to end the Israeli aggression on our people”, said an Islamic Jihad official. The delegation will reaffirm the group’s position that any exchange of hostages will have to secure the release of all Palestinians jailed in Israel, “after a ceasefire is achieved”, the official said.

Hamas and Islamic Jihad, both sworn to Israel’s destruction, are still believed to be holding more than 100 hostages from among 240 they captured during their Oct. 7 rampage through Israeli towns, when they killed 1,200 people.

Since then, Israel has besieged the Gaza Strip and laid much of it to waste, with more than 20,400 people confirmed killed, according to Gaza authorities, and thousands more believed dead under the rubble. The vast majority of the 2.3 million Gazans have been driven from their homes and the United Nations says conditions are catastrophic.

After a week-long truce collapsed at the start of the month, fighting has only intensified on the ground, with war spreading from the north of the Gaza Strip to the full length of the enclave.

The Israeli military said 10 of its soldiers had been killed in the past day, following five killed the previous day, its worst two-day losses since early November.

On Friday, Washington withheld its veto for the first time from a U.N. Security Council resolution on the war, allowing the resolution to pass after language calling for an immediate halt to hostilities was watered down.

On Saturday, Israel’s military chief of staff said his forces had largely achieved operational control in the north of Gaza and would expand operations further in the south.

But residents say fighting has only intensified in northern districts lately, notably Jabalia which Israeli forces were pounding with air strikes overnight and into Sunday. Tanks had moved further into the town on Saturday.

In the central part of the Gaza Strip, medics said six Palestinians were killed in an Israeli air strike on a house at the Bureij refugee camp, where the Israeli army ordered people to evacuate and head west towards Deir Al-Balah city.

Joudat Imad, 55, a father of six, had to leave an area in the Nusseirat refugee camp in central Gaza after a map published by the army marked it as a place people had to evacuate.

“I was lucky to get a tent in Rafah,” he told Reuters by phone. “From an owner of two buildings to a refugee in a tent awaiting aid — that is what this brutal war has turned us to. The world is sick and inhumane that it can’t see Israel’s brutality and it is helpless to stop this war of destruction and starvation.”

In Rafah, on Gaza’s southern border with Egypt, an Israeli air strike on a house killed two people, Palestinian medics said.

The Palestinian Red Crescent reported an attack on one of its main bases in Khan Younis in the southern Gaza Strip. It said a 13-year-old child had been shot dead by an Israeli drone while inside the Al-Amal Hospital.

The Israeli military has expressed regret for civilian deaths but blames Hamas for operating in densely populated areas or using civilians as human shields, an allegation the group denies.

The conflict has spread, as Yemen’s Iran-aligned Houthi forces disrupt global trade with missile and drone attacks on vessels in the Red Sea in retaliation for Israel’s assault on Gaza.

The United States shot down four drones launched from Houthi-controlled areas of Yemen towards a U.S. destroyer in the southern Red Sea on Saturday, bringing to 15 the number of such attacks on commercial shipping, U.S. Central Command said.

A drone launched from Iran struck a chemical tanker in the Indian Ocean on Saturday, the U.S. Defense Department said.