The Palestinian militant group Hamas has recruited between 10,000 and 15,000 members since the start of its war with Israel, according to two congressional sources briefed on U.S. intelligence, suggesting the Iran-backed fighters could remain a persistent threat to Israel.

After more than a year hiding in tunnels and dodging air strikes, uniformed Hamas fighters returned to the ruined streets of Gaza hours into a ceasefire, defying Israel’s vow to crush them. With the world watching on Sunday as Hamas handed over three Israeli hostages to the Red Cross,