Why Israel Seized the Philadelphi Corridor

Israel’s announcement on Wednesday that its forces had gained control over a strip of land that runs along the Gaza Strip’s southern border suggested that it had fulfilled one of the goals of the country’s war against Hamas, but it portends further isolation for Palestinians in the enclave.

Here’s a look at the importance of the border strip to Israel, to Palestinians and to Egypt:

What is the border strip?

It is land around 100 yards wide that runs roughly eight miles from Israel’s border to the Mediterranean. The new border, which divided the city of Rafah, was set up under the Egypt-Israel peace treaty of 1979. To the northeast is Gaza, while Egypt lies to the southwest. Egyptian border guards have been policing the land under an agreement with Israel made in 2005 when Israeli forces withdrew from Gaza. The Israelis used the code name Philadelphi for the strip, while Egyptian officials call it Salah Al Din.

Why does it matter to Israel?

Senior Israeli officials had set control of the strip, which in Israel is called the Philadelphi Corridor, as a military objective. Hamas had dug tunnels beneath the strip — some wide enough for trucks, according to military experts — and used them to smuggle weapons and personnel into Gazan territory.

“This is the way they can get in and out without asking the Israelis,” said Ahron Bregman, a political scientist and expert in Middle East security issues at King’s College in London, who is a former Israeli military officer. Unless the tunnels are blocked, he said in a previous interview, Hamas could rebuild its military capacity after the war.

Why does it matter to Egypt?

During other regional conflicts, Egypt has opened its borders to refugees, but the government of President Abdel Fattah el-Sisi fears that if Palestinian civilians crossed the border to escape the war they could destabilize the country and become a drag on its economy.

The government also sees Hamas as an adversary and does not want to give it a foothold in Egypt. Hamas began as an offshoot of the Muslim Brotherhood, an Islamist movement that was closely linked to the government that Mr. el-Sisi overthrew in 2013. His government has suppressed the Muslim Brotherhood since taking power.

Egypt has warned Israel to avoid doing anything that might force Gazans across the border or threaten a landmark peace agreement signed by the two countries in 1979.

For decades before the war, Egypt stationed guards along the Gaza border. It reinforced those forces after the Oct. 7 Hamas-led assault on Israel that set off the current fighting in Gaza.

Why does it matter to Palestinians?

Egypt is the only country other than Israel that borders Gaza, so Israel’s control of the corridor is likely to be viewed by Palestinians as a sign of increasing isolation.

At the same time, the tunnels have been used by Egyptian and Palestinian merchants to bring food and other goods into Gaza. Israeli control of the strip will likely halt that underground trade.