What to know as war between Israel and Hamas militants rages on for a fourth day

 Israel’s military said Tuesday that it had regained effective control over its south and the border with the Gaza Strip four days after Hamas fighters stormed into the country and brought gun battles to its streets for the first time in decades.

The declaration came as the Israeli Defense Forces sought to make good on the government’s vow to hunt down the militants and to intensify an assault on densely populated Gaza, the Palestinian territory ruled by Hamas and home to 2 million people.

The conflict already has killed hundreds on both sides. The Israeli military said more than 1,000 people have died in Israel since Saturday’s incursion. In Gaza and the West Bank, 830 people have been killed, according to authorities there.

Israel pounds Gaza neighborhoods, as people scramble for safety in sealed-off territory

Fighting escalates in war’s fourth day as Israel ups attacks on Gaza and Hamas vows to kill hostages

Who are Hamas? The group that rules the Gaza Strip has fought several rounds of war with Israel

In Israel and beyond, the families of more than 150 people kidnapped by Hamas and other militant groups feared for the lives of their loved ones. The armed wing of Hamas has warned it will kill one of the hostages every time Israel’s military bombs civilian targets in Gaza without warning.

Here are some key takeaways from the war:

WHAT IS HAPPENING ON THE GROUND?

Israel expanded its mobilization of military reservists to 360,000 on Tuesday, according to the country’s media. The chief military spokesman emphasized the unprecedented nature of the current campaign against Hamas, saying “all options are on the table.

The military said it struck hundreds of Hamas targets overnight in Gaza. Tens of thousands of residents fled their homes as relentless airstrikes leveled buildings, including in Gaza City’s residential and commercial district of Rimal.

Along with bombarding downtown Gaza City, Israeli airstrikes also targeted the crossing between Egypt and the city of Rafah in southern Gaza, the only passage out of the territory.

Over 137,000 Palestinians were packed into United Nations shelters, and the World Health Organization reported that the medical supplies it had pre-positioned in seven Gaza hospitals were already used up.

The head of Doctors Without Borders for the Palestinian Territories said he was concerned the humanitarian medical group’s team in Gaza would soon run out of medical supplies now that the enclaves borders have closed.

Leo Cans told The Associated Press he was particularly concerned about the supply of surgical equipment, bandages, antibiotics and fuel.

Prime Minister Benjamin Netanyahu declared in a televised announcement Monday that the offensive against Hamas in the Gaza Strip “has only started.”

“What we will do to our enemies in the coming days will reverberate with them for generations,” he said.

Hamas leaders have not spoken publicly about whether they anticipated Israel’s ferocious retaliation — or the potential risk of losing much of the group’s government infrastructure — when they launched the weekend attack.

WHAT HAS BEEN THE RESPONSE FROM THE U.S. AND OTHER NATIONS?

The U.S. is delivering critically needed munitions and military equipment to Israel, and the Pentagon is reviewing inventories to see what else can be sent quickly to boost its ally in the war with Hamas, a senior Defense Department official said Monday.

The official briefed reporters on the condition of anonymity to discuss sensitive shipments. The weapons movement came as President Joe Biden announced that the U.S. death toll in the war had risen to 11.

The war threatened to delay or derail a country-by-country diplomatic push by the United States to improve relations between Israel and its Arab neighbors. Hamas’ attacks in Israel and much of the Arab world’s response to it raised questions about whether Palestinian ambitions for sovereignty could be put aside during the so-called normalization push.

Foreign governments tried to determine how many of their citizens were dead, missing or in need of medical help or flights home from Israel. Japan’s top government spokesperson pledged to do the utmost to protect the safety of a small number of Japanese citizens in the conflict area.

Eighteen Thais were feared dead based on reports from employers, Thai Foreign Ministry spokesperson Kanchana Patarachoke said Tuesday. A first batch of 15 evacuees was scheduled to board a flight to arrive in Thailand on Thursday.

Ambassador to Israel Pannabha Chandraramya said the Thai Embassy was in touch with Israeli authorities about Thai nationals who were abducted by militant groups but has not been informed of their conditions or whereabouts.

The Austrian government said three Austrian-Israeli dual citizens may be among the people kidnapped by Hamas during its attack on Israel. Italy’s foreign minister said an Italian-Israeli couple living on the Be’eri Kibbutz had been missing since the incursion and were “probably taken hostage.”

Arab foreign ministers planned to convene Wednesday in Cairo at the behest of the Palestinians. Arab League Assistant Secretary-General Hossam Zaki said the ministers would discuss Arab efforts to “stop the Israeli aggression” on Gaza.

WHAT HAVE BEEN SOME OF THE RIPPLE EFFECTS OF THE WAR?

Major airlines have suspended flights in and out of Israel. Scores of arriving and departing flights at Tel Aviv’s Ben Gurion International Airport were canceled or delayed, according to the airport’s online flight board, which also showed a steady trickle of flights. Most were operated by Israel’s national airline El Al along with others by regional carriers such as Turkey’s Pegasus Airlines and Greece’s Blue Bird Airways.

Finnish carrier Finnair on Tuesday followed American Airlines, United Airlines, Delta Air Lines and German airline Lufthansa in suspending service to and from Israel.

Hong Kong leader John Lee said the government had issued a red outbound travel alert for Israel, becoming the latest government telling its citizens to avoid non-essential travel to the country.

Spanish multinational clothing company Inditex, owner of Zara, Massimo Dutti and other fashion brands, said it was temporarily closing its 84 franchised stores in Israel for security reasons.

WHY DID THE ATTACK TAKE ISRAEL BY SURPRISE?

Israel’s eyes appeared to have been closed in the lead-up to the attack by Hamas, which broke down Israeli border barriers and sent hundreds of militants into Israel.

“This is a major failure,” said Yaakov Amidror, a former national security adviser to Prime Minister Benjamin Netanyahu. “This operation actually proves that the (intelligence) abilities in Gaza were no good.”

Amidror declined to offer an explanation for the failure, saying lessons must be learned when the dust settles.

Rear Adm. Daniel Hagari, the chief military spokesperson, acknowledged the army owes the public an explanation. But he said now is not the time. “First, we fight. Then we investigate,” he said.

Some say it is too early to pin the blame solely on an intelligence fault. They point to a wave of low-level violence in the West Bank that shifted some military resources there and the political chaos roiling Israel over steps by Netanyahu’s far-right government to overhaul the judiciary. The controversial plan has threatened the cohesion of the country’s powerful military.

WHAT PROMPTED THE ATTACK?

Hamas officials cited long-simmering tensions, including a dispute over the sensitive Al-Aqsa Mosque sacred to both Muslims and Jews. Competing claims over the site, known to Jews as the Temple Mount, have spilled into violence before, including a bloody 11-day war between Israel and Hamas in 2021.

In recent years, Israeli religious nationalists — such as Itamar Ben-Gvir, the national security minister — have increased their visits to the compound. Last week, during the Jewish harvest festival of Sukkot, hundreds of ultra-Orthodox Jews and Israeli activists visited the site, prompting condemnation from Hamas and accusations that Jews were praying there in violation of the status quo agreement.

Hamas also has cited the expansion of Jewish settlements on lands Palestinians claim for a future state and Ben-Gvir’s efforts to toughen restrictions on Palestinian prisoners in Israel.

Tensions escalated with recent violent Palestinian protests. In negotiations with Qatar, Egypt and the United Nations, Hamas has pushed for Israeli concessions that could loosen the 17-year blockade on the enclave and help halt a worsening financial crisis.