JERUSALEM – Secretary of State John Kerry said Thursday that he had provided Prime Minister Benjamin Netanyahu of Israel with “some thoughts” about security arrangements that could be put in place if Israel and the Palestinians negotiated a peace agreement.

Kerry presented the ideas on security arrangements in the West Bank and in the Jordan Valley along with John R. Allen, a retired Marine general who was top commander in Afghanistan and is now advising the State Department on Middle East security issues.

The briefing appears to signify a more active U.S. role in the talks, one in which U.S. officials are not merely encouraging the Israelis and the Palestinians to negotiate but are also presenting their own proposals.

U.S. officials appear to be calculating that progress on security arrangements will enable discussions on the difficult question of what the borders of a new Palestinian state should be and other fundamental issues. But it was not clear if there was a meeting of U.S. and Israeli minds on security issues.

With Netanyahu by his side, Kerry told reporters after his morning meeting that the United States accepted the principle that Israel should be able to “defend itself by itself.”

But neither Kerry nor other U.S. officials have explained publicly what role, if any, the Israeli military might play in the Jordan Valley, the prime focus of security issues, if a peace treaty is agreed to or how long its presence there would last.

After meeting with Netanyahu, Kerry met in the West Bank city of Ramallah with Mahmoud Abbas, the president of the Palestinian Authority. Kerry was scheduled to meet with Netanyahu again Thursday night and perhaps this morning.

Although little detail has leaked from the negotiations room, it is clear that security arrangements in the Jordan Valley are a major sticking point in talks on borders and security.

Netanyahu has repeatedly insisted on maintaining a long-term Israeli military presence along the Jordan River and has dismissed the notion of reliance on international forces. Abbas, who agreed to a third-party presence in the past, has stated that there will be no Israeli soldiers in a future Palestinian state.

For decades, Israelis on the left and right viewed the eastern strip of the West Bank, which borders Jordan, as a crucial asset protecting Israel from threats from the east. With jagged slopes rising steeply from the valley floor, the corridor served as a natural buffer to detect and deter advancing forces.

Yitzhak Rabin, in his final address to Parliament as Israeli prime minister before his assassination in November 1995, said the “security border” for defending the state of Israel would be “in the Jordan Valley, in the widest sense of that term.”

On Thursday, Netanyahu reiterated his position, saying that Israel was ready for a “historic peace,” but one “that Israel can and must be able to defend by itself with our own forces against any foreseeable threat.”

But the radical changes of the past few years on the eastern front have made the Israeli demand to stay in the Jordan Valley all the more debatable – not only among Israel, its allies and the Palestinians but among Israelis themselves.

Critics of the Jordan Valley doctrine say the modern threat to Israel comes from rockets and missiles, making control of territory less important.