It seems as if Sunday's twin Hamas suicide bombings in Jerusalem and Ashkelon that killed 27 people including the attackers and wounded scores of others are being treated as the inevitable price of peace.

In what has become knee-jerk reactions to Hamas violence, Israel has again sealed off the West Bank and Gaza and urged Palestinian Authority chief Yasser Arafat to crack down on radicals in his midst. Arafat has predictably condemned the attacks as blows to the peace process, rounded up a hundred or so fundamentalists in a show of force and laughably ordered Palestinians to relinquish unlicensed weapons — as if Hamas members would comply.

Peres, determined to carry on the peace process, says Israel will get tough: It will delay leaving Hebron as called for under Oslo II; it will seal off its borders with the territories until after Israel's May 29 elections; and it will crack down on Hamas.

All fine and good, but far from enough. For unless Israel takes some more drastic steps, more Jewish lives will be lost to the Islamic culture of martyrdom.

Certainly Israel cannot make its borders airtight, nor prevent Hamas terrorists from boarding any of thousands of buses each day on bloodthirsty missions. Nor can Israel build Berlin Walls separating Jew from Arab — as much as some Israelis might be wishing that were so.

But Israel can do something simpler: It can hold Arafat's feet to the fire.

That means more than Arafat's token arrests of radicals — it means Arafat must do the Shin Bet's work, by infiltrating Hamas cells, busting them apart and going after the radical leaders. Israel has helped Arafat by handing him a list of its top 10 most-wanted figures. Let him deliver them to Israel.

Arafat must also see to it that the Palestinian Covenant is amended not just to stop urging Israel's destruction, but to promise peaceful coexistence with the Jewish state.

Meanwhile, Israel must not only seal off its borders and prevent Palestinians from working in Israel, it must stand still on the peace process by halting any peace talks or redeployment until Arafat produces results.

Arafat cannot be a sympathetic get-tough guy at his own convenience, but in reality afraid to get serious and provoke his more radical ranks.

When Arafat is forced to show real leadership, only then can Israelis lead saner lives free of fear that their buses might become coffins at any moment.