GAZA CITY, Gaza Strip — Israeli troops battled Hamas militants on Wednesday near a southern Gaza Strip town as the top U.S. diplomat reported progress in efforts to broker a truce in a war that has so far killed at least 684 Palestinians and 31 Israelis.

But neither side appeared close to backing down, after Palestinian rocket fire led several international airlines to cancel flights to Tel Aviv and Israeli troops clashed with Hamas fighters near the Gaza town of Khan Younis, forcing dozens of families to flee.

Israel has insisted it must substantially curb the military capabilities of the Islamic militant group Hamas — a position that appears to have gained support within the U.S. administration — while Hamas has demanded the lifting of a crippling Israeli and Egyptian blockade on the impoverished coastal territory.

U.S. Secretary of State John Kerry flew into Tel Aviv despite a Federal Aviation Administration ban following a Hamas rocket that hit near the airport the day before, reflecting his determination to achieve a cease-fire agreement between the warring sides.

He was to meet with Israeli Prime Minister Benjamin Netanyahu after earlier meetings with Palestinian President Mahmoud Abbas and U.N. chief Ban Ki-moon. But U.S. officials have downplayed expectations for an immediate, lasting truce.

In Jerusalem, Kerry said negotiations toward a Gaza cease-fire agreement were making some progress, describing unspecified steps forward in the negotiations as he met for a second time this week with Ban.

“We certainly have made steps forward,” Kerry said, adding, “There’s still work to be done.”

White House deputy national security adviser Tony Blinken meanwhile said Hamas must be denied the ability to “rain down rockets on Israeli civilians.”