The Israel-Hamas War Has Entered a ‘New Phase.’ Here’s What to Expect.

Israel has entered “a new phase in the war” against Hamas in Gaza, Israeli Defense Minister Yoav Gallant said on Saturday. The Israel Defense Forces (IDF) has sent tanks and other ground forces into Gaza and kept them there while continuing its intense artillery attacks and aerial bombardment, but for now it has held off on an all-out ground invasion. It is not clear if there will ever be a formal D-day for such an operation, but Israel is steadily increasing its ground operations within Gaza, conducting raids into the strip and severing telecommunications there.

As Israel shifts from an air-only approach to one involving its ground forces, it is coming face-to-face with many challenges and even more dilemmas, some of which involve risks to Israeli troops while others concern broader strategic and humanitarian objectives. Already, these challenges may have delayed a full-scale invasion of Gaza, and they could cause Israeli leaders to limit the scope and scale of military operations in other ways as well.

The first challenge is the very nature of the fighting. Gaza is built-up and densely populated, with a population per square mile comparable with London. In its warren of narrow streets and tightly packed buildings, many of the Israeli military’s advantages in speed, communications, surveillance, and long-range firepower are neutralized.

Instead, the IDF will need to break up its forces, which will then be vulnerable to small bands of Hamas gunmen. The rubble created by Israeli bombing also offers opportunities for small groups of fighters to find cover against Israeli troops, set up sniper positions, and plant booby traps.

The U.S. military found urban operations in Fallujah, Iraq, difficult and highly destructive. Gaza is likely to be even harder. Unlike the Iraqi insurgents whom the United States was fighting in Fallujah in 2004, who had only recently taken control of the city, Hamas has controlled Gaza since 2007 and has fought Israel there several times since. The group probably anticipated a tough Israeli response to its Oct. 7 attack, but even if it didn’t, Hamas has long prepared for an Israeli incursion.

Hamas has collocated military supplies and assets in civilian facilities such as schools, according  to the United Nations as well as Israeli forces. The group has also built a vast tunnel network, thought to be larger than the London Underground. It can use these tunnels to hide supplies and leaders, as well as to ensure communication during conflict.

Tunnel fighting is a nightmare. The former head of U.S. Central Command, Gen. Joseph L. Votel, compared it with the Islamic State’s use of a tunnel network in Mosul, Iraq—which was a fraction of the size of Hamas’s tunnels)—and warned, “It will be bloody, brutal fighting.” Hamas fighters may use the tunnels to pop up behind Israeli forces, ambushing them or even capturing more hostages. Israel has tried to bomb these tunnels, but they are difficult to find and destroy from the air.

Israel seeks to destroy Hamas, which in practice means killing its leaders. They are proving difficult to find, however. They can hide in tunnels and blend in with the civilian population. Some will choose to fight, but the organization is well-institutionalized, and it will undoubtedly seek to preserve much of its leadership cadre, including key figures such as Hamas military commander Mohammed Deif.

Israel, in the past, has successfully targeted Hamas and other leaders, but this was a slow process, and even an occupation of northern Gaza would mean that Israel would not control large parts of the strip, allowing Hamas leaders to hide there. What’s more, many of Hamas’s senior political leaders don’t live in Gaza at all, but rather spend their days in much safer locales in countries such as Qatar, Turkey, and Lebanon.

Making this even harder are the more than 200 hostages Hamas has taken, which include many foreign nationals, including 54 Thai workers and around 10 Americans. At the very least, this will complicate the fighting: A building where Hamas leaders are hiding may also have hostages in it, as might a tunnel where Hamas supplies are kept. Sending troops in to attack these locations, let alone simply blowing them up, could kill the hostages.

In addition, Hamas has threatened to kill the hostages in response to Israeli attacks. It has not yet fulfilled this vow, as far as we know, but it could do so in the future. Indeed, the more successful that Israel’s ground operation is at striking Hamas, the more likely the organization would resort to desperate measures.

Israel also must consider the civilian cost in Gaza. Its operations there have already killed almost 7,000 Palestinians, according to the strip’s Hamas-run health ministry, and ground operations may be far bloodier. In the past, international outrage at civilian casualties has, eventually, led Israel to stop operations, though the exceptionally high Israeli death toll from Hamas’s Oct. 7 attack may change this calculus. This concern will complicate combat as Israel tries to balance the civilian toll with the risk to its troops, as well as the likelihood that Hamas is mixing fighters and military assets among the civilian population.

Outside of its immediate operations, Israel has denied fuel, electricity, and other civilian necessities to Gaza on the grounds that Hamas will use these for military purposes. Already, this has created a massive humanitarian crisis, and this will only worsen as the days go on. If Israel bows to U.S. and international pressure to provide basic services and ensure that food and medicine flow into the strip for civilians, it will be in the unusual position of providing aid and waging war in the same area. Yet if it fails to do so, the already-high human cost will skyrocket, with children, older adults, and other noncombatants paying the price.

Although Israel’s own strategic interests and its leaders’ desire to assuage a shocked and angry public will be the primary shapers of military operations, Israeli leaders also must care about international, and especially U.S., opinion. Many Arab leaders privately loathe Hamas and would be delighted if Israel destroyed it.

Their publics, however, are pleased that Israel has been hit hard and outraged at the destruction that Israel is raining down on Gaza. Israeli operations have led to protests throughout the Arab world, including in countries such as Bahrain and Egypt, which have normalized relations with Israel. This normalization is a top diplomatic goal for Israel, and it will not jeopardize this lightly. Even Saudi Arabia, which until the war broke out was in intense negotiations with the United States to cement a normalization deal with Israel, has issued increasingly strident statements condemning Israel’s actions in Gaza.

Even more important is U.S. opinion. President Joe Biden and his administration have embraced Israel publicly but privately seem to be urging restraint. In addition to seeking to limit the human cost on the Palestinian side, officials in Washington are concerned about the risk to American hostages and the danger that the conflict will spread throughout the region and threaten U.S. forces and allies. As these worries mount, U.S. pressure on Israel to curb its operations may grow.

U.S. fears are well-founded, as it is possible this war may spread from Israel and Gaza to much of the Middle East. Already, Hezbollah has threatened to join the fray and stepped up attacks on Israel from Lebanon, unrest is growing in the West Bank, the Houthis in Yemen have launched missiles at Israel, and U.S. bases in the Middle East have suffered attacks from Iranian proxies, leading the United States to strike Iran-linked sites in Syria. A broader war involving Hezbollah and other Iranian-backed groups would pose a grave threat to Israel, increase the risk of international terrorism, and implicate many U.S. interests.

Israel will face even more fundamental challenges when it seeks to end military operations. One difficulty in uprooting Hamas is the question of who—or what—would take its place. The Palestinian Authority is barely hanging on to the West Bank, and it would damage its already weak credibility among Palestinians if it collaborated with Israel in running Gaza in the aftermath of an invasion. Egypt and other Arab states are reluctant to take in Palestinian refugees, let alone take on the messy task of administering Gaza.

But if Israel simply strikes hard and leaves, Hamas will reassert itself, with no one to contest its control. Polls show that Hamas is not popular, but they also show that its Palestinian rivals are even less so—and they lack the military assets and the social and economic networks that Hamas has in Gaza.

Anger in Israel is white-hot, demanding Hamas’s destruction, but Israeli leaders know that operations will be risky and could easily prove counterproductive. The risk of further Israeli casualties and other concerns are probably leading some in the Israeli government, perhaps including the prime minister himself, to tread cautiously.

The final result may involve some ground operations, but is likely to be a more cautious approach in general than the all-out invasion and long-term occupation that seemed likely in the immediate aftermath of the Oct. 7 attacks. Such an approach would not destroy Hamas and will still lead to Israel casualties and far more suffering on the Palestinian side, but it would allow Israeli leaders to minimize many of the most difficult dilemmas that they face in Gaza.