Israeli forces were battling Palestinian militants across the Gaza Strip on Sunday, including in parts of the devastated north that the military said it had cleared months ago, where Hamas has exploited a security vacuum to regroup.

Israel has portrayed the southern Gaza city of Rafah as Hamas’s last stronghold, saying it must invade in order to succeed in its goals of dismantling the group and returning scores of hostages. A limited operation there has expanded in recent days, forcing some 300,000 people to flee and drawing warnings from Egypt, where an official said it is putting the country’s decades-old peace treaty with Israel at risk.