Hard to Turn Back

ISRAEL took six days to capture the West Bank; 28 years to return just its towns to Palestinian control.

In exchange for that partial return, Israel gets something less than uninterrupted peace. But the essential meaning of the agreement Yasser Arafat and Yitzhak Rabin sign in Washington Thursday is that both sides have invested so heavily in the long chain of moves called peace that neither can turn back.

Nowhere has that momentum toward further stages on the road to coexistence been more apparent than in the speed with which each side returned to the negotiations after inflammatory incidents. In the past a Hamas attack on an Israeli bus or a Jewish settler attack on a Palestinian school would have caused a lengthy break. In the crucial recent period there was virtually no pause.

Mideast hands had feared that when Mr. Arafat saw on maps how much territory Israeli troops would continue to control, he might halt the talks. He did explode. But he was soon back to conclude the deal.

His emotion was understandable. After 1967, much of the world believed the newly occupied West Bank would be returned to its residents with only minor border adjustments for Israeli security. What has happened is much different. Israeli forces will control large tracts of unpopulated ''state lands,'' much of it hilltops. And there will be shared Israeli-Palestinian authority in rural areas. Only cities and towns revert to Palestinian control.

Ironically, this shift from minor border adjustments to the Swiss- cheese look mapped in this week's 400-page agreement comes at a time when Israel's forward security line has really become the Iraqi border. It's significant, not just stagecraft, to have Jordan's King Hussein and Egypt's President Hosni Mubarak invited to the White House ceremony. The king, Israel, and Washington all have been quietly nudging forward changes in Baghdad. Ultimately, each hopes for a regime the West can do business with.

The combination of Palestinian-Israeli momentum and possible change in Iraq would put pressure on Syria to get on with peace negotiations leading to a return of the Golan. And that, in turn, could lead to talks about Syrian and Israeli withdrawal from Lebanon.

Such moves toward building prosperity instead of destructiveness in the region will not occur, though, unless the Palestinian-Israeli deal first tips the balance toward a better life for the Palestinians and more calm for Israel. There may be no going back now. But the going forward has to prove genuine.

Both have invested so heavily in the chain of moves called peace that neither can retreat.