Defense Secretary Leon E. Panetta warned on Sunday that Israel was becoming increasingly isolated in the Middle East, and said Israeli leaders must restart negotiations with the Palestinians and work to restore relations with Egypt and Turkey.

Mr. Panetta told reporters traveling with him that while Israel is still the most powerful state in the region, “Is it enough to maintain a military edge if you’re isolating yourself in the diplomatic arena?” He continued, “Real security can only be achieved by both a strong diplomatic effort as well as a strong effort to project your military strength.”

Mr. Panetta is scheduled to meet this week with Israeli and Palestinian leaders, and then to travel to a meeting of NATO defense ministers in Brussels.

“It’s pretty clear that at this dramatic time in the Middle East, when there have been so many changes, that it is not a good situation for Israel to become increasingly isolated,” he said. “And that’s what’s happening.”

Israel has seen its once-friendly relations with Turkey sour over Israel’s commando raid last-year on a Gaza-bound flotilla. And the revolts of the Arab Spring have toppled leaders with whom Israel could do business, like Hosni Mubarak of Egypt, and given vent to anti-Israel sentiment across the region.