The hostages in Gaza are on the move, with Hamas moving some from apartment to apartment to hide their location, while others are believed to be in underground tunnels.
Meanwhile, a “fusion cell” quietly formed in Israel last fall brings together U.S. and Israeli intelligence and military analysts sharing drone and satellite imagery, communications intercepts and any other intelligence that might lead to the hostages' location.
There are multiple wars being waged in the Gaza Strip.
While the world focuses on Israel's air strikes and ground invasion aimed at dismantling Hamas, reducing much of its territory to rubble and sparking a humanitarian crisis, Saturday's rescue of the four hostages was a reminder that Israel and Hamas are fighting a different, less visible battle.
The militants are determined to hold on to the hostages they captured in the deadly Oct. 7 attack on Israel to use them as bargaining chips, and Israel is determined to bring them home.
For more than eight months, extremists have had the upper hand.
Israeli and US officials say they don't know where many of the hostages are being held, and even if they did, a rescue mission would often be impossible.
Israel has rescued a total of seven hostages so far, but the harsh reality is that many more have died in fighting or at the hands of Hamas since the war began, and Israel has recovered many more bodies than surviving hostages.
While there was jubilation over the rescue effort that began in Israel on Saturday, Israeli and U.S. officials said the complexity of the operation itself and the violence it entailed highlighted the difficulty of finding and rescuing the hostages. One rescuer was killed, Israeli special forces killed numerous Hamas fighters, and dozens of civilians were killed in the firefight. Hamas also said three other hostages were killed in Israeli airstrikes, but an IDF spokesman denied that.
It's also unclear how many more ground rescue raids there will be — so far all the hostages have been rescued from apartments — and current and former Israeli and US officials say Hamas is changing tactics, moving more hostages into tunnels, out of reach of special forces.
US and Israeli officials say the rescue mission is an exception in reality, and only diplomatic means can bring home most of the remaining hostages. US officials are pressuring Israel and Hamas to agree to a deal to return the hostages as part of a ceasefire.
“We must remember that the release of the four hostages is ultimately a tactical achievement and does not change the strategic side of things,” said Avi Karo, a former Israeli reserve lieutenant colonel who previously headed the military intelligence division that handles prisoners and missing persons. “Hamas still holds dozens of hostages, and most, if not all, will not be released in the operation and can only be rescued as part of a ceasefire agreement.”
Freeing the hostages has been a priority since the war began, but some U.S. officials say Israel's focus on the goal has varied. The December shooting and killing of three fleeing men in northern Gaza, unintentionally killing three hostages, revealed that the Israeli military has not always been sensitive about searching for hostages. Israeli officials say the military has learned from the mistake.
Israeli authorities said 251 people were believed to have been captured in the October 7 terror attack, 105 of whom were released following a deal between Israel and Hamas last November.
since then, Of the remaining hostages, 43 have been officially declared dead; many, but not all, are believed to have died in captivity. Israeli officials have privately said they believe fewer than 60 are still alive. US officials say five are dual nationals. The bodies of civilians still alive in Gaza and three Americans held captive by Hamas.
Throughout its history, Israel has tried every possible means to bring hostages home. It has been a long-established principle to first use military force to rescue Israelis. When rescue is not possible, Israel will make deals, sometimes offering more than 1,000 Palestinian prisoners for every captured Israeli soldier.
The British are also involved in the operation to track the hostages' movements, but the goal is not just to pinpoint their locations. Military and intelligence officials are also looking for patterns, trying to understand how long Hamas holds hostages in one place before moving them elsewhere. Identifying patterns can help them better gauge the time frame for a rescue operation.
The intelligence gathered is often piecemeal: hints that certain hostages are still alive, or clues about the group that may be holding them, don't reveal exact locations, but they do give hints as to which parts of Gaza to step up intelligence gathering. No one knows how reliable the information is, but once the Israelis have a reasonable idea of ​​a location and believe the hostages may be there for a while, careful planning begins.
Early in the war, some intelligence officials believed most of the hostages were being held in the tunnels, but life underground proved too tough for Hamas commanders, who apparently found it easier to lock them in the apartments of the group's supporters.
As the war dragged on, Israel's ability to gather intelligence on the hostages improved, thanks to seized documents, interrogations of captured Hamas fighters, and assistance from the United States and Britain.
Israeli and American officials believe some of the hostages may be more mobile than they were at the start of the war, but given Israel's devastating attacks on the tiny territory, Hamas has a smaller area in which to hide them, increasing its chances of finding them, American and Israeli officials said.
Moreover, as travel in the Gaza Strip has become more difficult, communication between Hamas brigades and the central leadership has been cut off, U.S. officials said, leading some hostages to remain in hiding longer.
US officials believe Hamas is responsible for the treatment of all the hostages, but because some are not in Hamas custody and are in the custody of allied militias, such as Palestinian Islamic Jihad, Hamas leaders are unsure of how many hostages there are in Gaza, US and Israeli officials said.
Israeli and American officials have become increasingly concerned about the health of the hostages, who have suffered mental and physical abuse during their long captivity.
“The hostages are so mentally and physically weakened by nearly nine months of captivity that their rescuers may not even recognize them,” said Gen. Richard D. Clark, the retired head of U.S. Special Operations Command.
While Israel is desperately searching for the hostages, Hamas leaders are trying to keep them hidden, knowing that they will have the greatest leverage in ceasefire negotiations.
But they also have another role: a small group of hostages are believed to be being held near Hamas leader Yahya Sinwar in the Gaza Strip, acting as human shields and making it harder for Israel to attack him.
The US and Israel have struggled to pinpoint Sinwar and the hostages' exact location, but US officials say he has been moving around the Gaza Strip, at one point hiding out underground in Rafah, but is now likely back underground in Khan Yunis, Gaza's second-largest city. The network of tunnels there is so vast that neither the U.S. nor Israel has been able to pinpoint his exact location, U.S. officials said.
According to Israeli officials, Hamas leaders have given standing orders to their fighters who hold hostages to shoot them first if they sense Israeli forces are closing in. If hostages were killed on Saturday, as Hamas claims, it may have been at the hands of militants rather than Israeli airstrikes. But so far Israeli and US officials have been unable to confirm or refute Hamas' claim.
U.S. forces have been flying surveillance drones over the Gaza Strip since shortly after the Israeli attack on Oct. 7 to help with hostage rescue efforts, U.S. officials said. At least six MQ-9 Reapers piloted by special forces are engaged in flying missions to monitor for signs of life, the officials said.
An Israeli official said the British and American drones were able to provide intelligence that Israeli drones were not collecting. U.S. surveillance drones are equipped with nearly the same sensors as their British and Israeli counterparts, U.S. military officials said, but the sheer number of U.S. aircraft allows them to monitor larger areas more frequently and for longer periods of time.
While drones cannot map Hamas' vast underground network of tunnels — Israel uses secret ground sensors for that — infrared radar can pick up heat signatures from fighters and others entering or exiting tunnel entrances above ground, the officials said.
Intelligence sharing between the United States and Israel related to the Gaza war initially focused on hostage rescue efforts but cooperation has expanded over time, three current and former senior U.S. officials said.
“This is part of the largest intelligence operation Israel has ever seen, and probably has ever seen,” Caro said of the US and Britain.
Adam Goldman He contributed reporting from Washington.