US Defense Secretary Leon Panetta said the Arab spring has left Israel "increasingly isolated" in the Middle East and that its military might could not make up for a weakened diplomatic position.

Speaking to reporters aboard his plane bound for Israel as part of a Middle East tour, Panetta said it was crucial for Israel to shore up its relations with Egypt and other countries in the region that had proved valuable partners in the past.

"There's not much question in my mind that they maintain that (military) edge. But the question you have to ask is it enough to maintain a military edge, if you're isolating yourself in the diplomatic arena?" Panetta said.

"At this dramatic time in the Middle East, when there have been so many changes, it's not a good situation for Israel to become increasingly isolated. And that's what's happening," he said.

Panetta, who was due to meet Israeli and Palestinian leaders on Monday before heading to Egypt and a NATO session in Brussels this week, said Israel needed to repair diplomatic ties with countries such as Egypt and Turkey and that Washington was ready to help.

"I think for the security of that region, it's really important that we do everything possible to try help them reestablish relations with countries like Turkey and with Egypt," said Panetta.

With the end of Hosni Mubarak's rule in Egypt and popular unrest elsewhere casting doubt on the premises underlying Israel's security, Panetta said Israeli leaders were fully aware of the difficult challenge they faced.

"I think they recognize that it's important to try to do whatever they can to try to improve those relations," he said.

A spokesman for Panetta, George Little, said the Pentagon chief viewed Israel's isolation as the product of its own actions as well as events outside of its control, including Iran's support for militants hostile to Israel.

In his talks with his Israeli counterpart, Defense Minister Ehud Barak, and other Israeli and Palestinian leaders, Panetta said he would be urging both sides to return to the negotiating table.

"My main message is to both sides, you don't lose anything, you don't lose anything by going into negotiations."

He repeated the US administration's stance that the Palestinians should pursue their goal of statehood through peace talks and not through a UN resolution.

"One thing that's been made clear, it's been made clear by the (US) president, it's been made clear by the secretary of state, is that you're not going to achieve Middle East peace by trying to slam dunk it in the UN.

"The only way you're going to achieve it is by negotiations."

Panetta's visit comes amid concern in Washington that the Palestinians' push for UN recognition could raise popular expectations that will end in disappointment and potential violence, following an expected veto of the move by the United States.

Panetta will be appealing to Palestinian leaders to try to contain any possible violence, a senior defense official said.

The United States has "an interest in maintaining security and stability in the West Bank at a time when people have understandably expressed concern that with the emotions stirred up by the events in New York, there could be new tensions and even incidents of violence on the ground," the defense official, who spoke on condition of anonymity, told reporters.

"And we certainly want to encourage both sides to tamp that down."

The Pentagon chief also planned to call on both Israeli and Egyptian leaders to work to defuse tensions on their common border that have grown since street protests in Cairo ousted Mubarak as president, the defense official said.

In Israel, Panetta said he planned to discuss the threat posed by Iran with Israeli leaders, but appeared to discourage a possible pre-emptive strike by Israel against Tehran's nuclear sites.

"I think the most effective way to deal with Iran is not on a unilateral basis," he said.

In talks this week in Cairo, Panetta said he would express his appreciation to interim military rulers for intervening during riots last month targeting the Israeli embassy and to reaffirm Washington's longstanding military ties with Egypt.

He said he would also urge Egypt's military rulers to press ahead with plans to hold elections that will secure democratic rule, "so that Egypt can move towards a civilian government that represents the will of the people."