JERUSALEM — As I wander along the spectacular stone walls of Jerusalem's Old City, which sparkle in the bright morning sun on the 40th anniversary of the Six-Day War, I'm struck by a sobering thought.

I've been coming to Israel for 40 years. I remember arriving not long after the euphoric Israeli victory in a war that followed drastic threats from Syria and Egypt. For the first time since Israel's inception, its major cities were out of range of Arab guns and Jerusalem was reunited.

But Israel had not expected to wind up in possession of the West Bank of Jordan or East Jerusalem. Ever since, Israelis have debated whether their security interests would be better served by giving up that territory, or even the Arab parts of Jerusalem.

Americans are often ignorant of how intense this debate is — even when the peace process is in a coma. On this anniversary, it's worth recalling why so many Israelis have been debating the fate of the West Bank for decades.

Israelis understand the territorial legacy of the Six-Day War is a burden that grows more dangerous the longer the occupation. The well-known Israeli journalist Tom Segev wrote in the New York Times this week that Israeli planners warned six months prior to the war that a West Bank occupation would undercut Israel's Jewish majority and lead to violent resistance.

Akiva Eldar, dean of Israeli commentators, wrote this week in Ha'aretz of a missed chance to unload the West Bank in 1967. Right after the war, an Israeli Mossad agent, David Kimche, met the prominent Palestinian attorney Aziz Shehade, who told him leading West Bankers were ready to sign a peace treaty with Israel in return for a state. But Kimche was unable to interest his superiors in this proposal.

Eldar believes that the longer the occupation lasts, the more radical the Palestinian population will become. I visited him this week in his apartment overlooking the Mediterranean. He insisted: "The status quo (in the West Bank and Gaza) is not an option. Continuing the occupation gives a gift to radical Palestinian groups that are worse than (the Islamist group) Hamas."

During my early visits to Israel, Israeli and Palestinian intellectuals visited one another freely and spoke at one another's universities. Saeb Erekat, now a top aide to Palestinian president Mahmoud Abbas, used to drive to Haifa to give lectures. Tens of thousands of Palestinians worked in Israel. Palestinians swam at Tel Aviv beaches; Israelis went to Nablus to get their cars fixed. I used to hear Hebrew spoken in the Gaza market.

But Israeli officials were unwilling back then to deal with genuine leaders inside the West Bank and Gaza. The Israeli settlement movement was allowed to expand its housing across the West Bank, undercutting those leaders.

Even so, those Israeli-Palestinian contacts helped produce the 1993 Oslo peace accords between Israel and the Palestine Liberation Organization. Why did hawkish Prime Minister Yitzhak Rabin make this deal? For the same reasons laid out by Segev and Eldar: the demographic threat, and the fear that occupation would further radicalize Palestinians.

There's no space here to rehash why the Oslo accords failed. Both sides bear their share of the blame. Today, the West Bank and Gaza are totally cut off from Israel, with almost no contact between peoples. The lockdown of the Palestinian population — for security reasons, and to protect Israeli settlers — has destroyed the economy and collapsed Palestinian institutions. Islamists and criminal groups are filling the vacuum, and Gaza's anarchy threatens to spread to the West Bank.

So I'm not surprised that, on this anniversary, thoughtful Israelis still argue they must rid themselves of the burden they acquired in 1967. No one is certain how to do it, but they know it will be far more difficult now than back then. Yet mistrust between Israelis and Palestinians is so high, and their leaders so weak, that they cannot do it alone. Progress can happen only if the Bush administration finally puts muscle behind the president's rhetoric about a Palestinian state.

Israelis such as Deputy Defense Minister Ephraim Sneh, a brigadier general who headed the Israeli civil administration of the West Bank from 1985-87, say there is only one hope: "Start negotiations on final status with (Abbas) as soon as possible."

Otherwise, it's frightening to think what the West Bank will look like on the 50th anniversary of the Six-Day War.

Trudy Rubin is a columnist and editorial-board member for the Philadelphia Inquirer. Reach her at trubin@phillynews.com.