Around 1,500 bodies of Hamas militants have been found in Israeli territory, the Israeli military said Tuesday after announcing it had largely gained control in the south and “restored full control” over the border on the fourth day of fighting following an unprecedented surprise attack.

Spokesperson Richard Hecht said no Hamas fighters have crossed into Israel since Monday night, although infiltrations could still be possible. Israel has previously reported 900 soldiers and civilians killed, and Palestinian authorities have reported about 700 deaths in Gaza and the West Bank.

The Israeli government promised Monday to hunt down Hamas fighters and to punish the Gaza Strip following a surprise weekend attack that killed more than 900 people in Israel, including at least 260 at a crowded music festival that became the scene of one of the country’s worst civilian massacres.

During an unprecedented incursion Saturday, militants blew through a fortified border fence and gunned down civilians and soldiers in Israeli communities along the Gaza frontier during a Jewish holiday. Israel struck back with airstrikes, including one that flattened a 14-story tower that held Hamas offices.

Read: Israel strikes downtown Gaza City and mobilizes 300,000 reservists as war enters fourth day

Here are some key takeaways from the war:

WHAT IS HAPPENING ON THE GROUND?

The Israeli military said it had secured the border and had largely gained control in the south after mobilizing 300,000 reservists, raising the question of whether Israel will launch a ground assault into the tiny Mediterranean coastal territory. It would be the first since 2014.

The military said it struck hundreds of Hamas targets overnight into Tuesday in Gaza’s City Rimal neighborhood. Tens of thousands fled their homes as relentless airstrikes leveled buildings, including in Gaza City's residential and commercial district of Rimal and earlier in the southern city of Rafah.

WHAT HAVE BOTH SIDES VOWED TO DO?

Israeli Defense Minister Yoav Gallant said he had ordered a “complete siege” on Gaza and that authorities would cut electricity and block the entry of food and fuel to the Palestinian territory. Military spokesperson Richard Hecht said Tuesday that government and civilian ministries, such as Parliament and the social welfare ministry, could be targeted.

Hamas, meanwhile, pledged to kill one Israeli civilian captive any time Israel targets civilians in the Gaza Strip without warnings. Hamas and other militants in Gaza say they are holding more than 130 soldiers and civilians taken from inside Israel.

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,” Netanyahu said.

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

Asian countries were working to ensure the safety of their citizens who were still in conflict areas Tuesday, with 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, condemning Hamas and Palestinian militants over their attacks on citizens.

Eighteen Thais are feared dead based on reports from employers, while the numbers of those injured and abducted stand at 9 and 11 in the fourth day of the latest Israel-Hamas war, Thai Foreign Ministry spokesperson Kanchana Patarachoke said Tuesday. The first batch of 15 evacuees is scheduled to board a flight to arrive in Thailand on Thursday. Thai Ambassador to Israel Pannabha Chandraramya said the embassy is in touch with Israeli authorities about Thai nationals who have been abducted, but has not been informed of their conditions or whereabouts.

Hong Kong leader John Lee said Tuesday the government had received requests for assistance from 28 Hong Kongers, and 20 of them already left Israel. Authorities will keep in contact with the remaining eight and make arrangements according to their needs, he added. Lee said in his weekly press briefing that the government issued a red outbound travel alert for Israel, becoming the latest government telling its citizens to avoid non-essential travel to the country.

Read: Israel's Netanyahu says offensive against Hamas will 'reverberate' for generations

The U.S. has already begun 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 3-day-old war with Hamas, a senior Defense Department official said Monday. The official briefed reporters on 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 has gone up to 11.

The leaders of numerous Western nations, including Britain and Germany, have condemned the attacks by Hamas, while Arab nations have urged that the fighting on both sides stop.

Arab foreign ministers plan 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.

Supporters of Israel and backers of the Palestinian cause held competing rallies Sunday in several American cities and Monday in London; Athens, Greece; and France.

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.

American Airlines, United Airlines and Delta Air Lines suspended service as the U.S. State Department issued travel advisories for the region citing potential for terrorism and civil unrest.

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.

Read: The US will send a carrier strike group to the Eastern Mediterranean in support of Israel

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.