The ground is shifting in the Middle East, and this doesn’t bode well for Israel.

America is slowly but surely beginning to plan its departure from Iraq. President Bush has a new secretary of defense with new policy advisers who favor negotiating with Israel’s enemies to take the pressure off Iraq. The prospect of an Iranian nuclear bomb grows steadily greater as an American military strike against Tehran is ruled out and Europe demonstrates that it lacks the will to apply economic sanctions.

Radical Islam continues to gain ground. Hamas is on its way to obtaining international acceptance of a Palestinian government controlled by it, without having first to agree to recognize Israel and stop firing rockets from Gaza. The provisions of Security Council Resolution 1701, which called for an end to the arming of Hezbollah and for the removal of its troops from southern Lebanon, are not being enforced by the enlarged United Nations Interim Force in Lebanon. Syria, which several months ago was isolated and in international disrepute, has been relegitimized and is back in the picture.

In many respects, the first six years of the Bush administration, which were a golden period in Israel’s relations with Washington, have been wasted. Never before has such a pro-Israel president sat in the White House. And in all probability, never again will there be one like him, either. If ever there was a time to use American support to permanently change Israel’s situation for the better, this was it. And indeed, Ariel Sharon’s disengagement plan, had it been extended to the West Bank with American backing, could have done just that.

But disengagement stalled after the pullout from Gaza in the summer of 2005. First came Mr. Sharon’s stroke. Next, the rockets from an evacuated Gaza that Israel’s army couldn’t stop. Then the botched war in southern Lebanon, which seemed a grim warning of what could happen if Israel left the West Bank unilaterally. And to top it all off, the Bush administration never threw its weight behind West Bank disengagement as it might have, mainly because it would not have involved — as Gaza did — a total Israeli withdrawal to the 1967 borders. The opportunity was lost. It’s not going to return.

In general, time is not now in Israel’s favor. The current trends are running against it. And this is why it is sadly insufficient for it to behave as it has been doing under the government of Ehud Olmert, which is acting as though there were all the time in the world and Israel just had to sit still and let things progress in its favor.

Take, for instance, the new European “peace initiative” put forward by the trio of Spain, France, and Italy. In itself it’s a fairly meaningless proposal, full of nice phrases and no realistic ideas, and Israel has every reason to be suspicious of both European intentions and European levels of performance. In the case of Lebanon, indeed, Europe has confirmed Israel’s worst fears by doing nothing to carry out those parts of Resolution 1701 whose implementation alone could have justified Israel’s going to war.

And yet it is foolish for Israel to reject this proposal, as it has done, “out of hand,” to quote the words of Israel’s foreign minister, Tzipi Livni, while the Arab countries and even Hamas welcome it. This is not only bad public relations, since it once again puts Israel in the position of the intransigent party that is not interested in peace, it also is bad diplomacy. With America’s influence in the Middle East having peaked and begun to wane, Israel can no longer say “To hell with Europe” and lean exclusively on America, even if European hypocrisy and European duplicity are as great as ever. Europe is in any case going to fill much of the Middle East vacuum created by America’s coming retrenchment, and Israel had better make the most of it.

It might begin with the new “peace initiative”— and with Lebanon and Iran. Instead of the gruff “no thank you” given by Foreign Minister Livni, she might have responded: “We welcome the new European initiative. Indeed, we would like to explore it further. Europe needs to play a major role in helping us to solve our problems with the Palestinians and the rejectionist Arab states. But first, Europe has to demonstrate to us that it is dependable. It already has a role in Lebanon that it isn’t fulfilling. It already has a stated policy of stopping Iranian nuclearization that it isn’t carrying out. As much as we might like to, we can’t consider giving it new roles — a European version of UNIFIL in the Gaza Strip, for instance, such as some European diplomats have suggested — until it does better with the obligations it already has. Show us that it can meet them and we’ll be receptive to more.”

In the long run, if America isn’t going to provide the muscle for an Israeli withdrawal from most of the West Bank, the inclusion of Europe — perhaps even of a European peacekeeping force in the evacuated areas — is the only alternative. This is a possibility that is still a long way off, in terms of both European attitudes and Israeli attitudes. But Europe and Israel need to change the way they think about one another. For a short while, during last summer’s war in Lebanon, when most European countries supported Israel against Hezbollah, it seemed that this was happening. Then it foundered. It’s time to try again.

Mr. Halkin is a contributing editor of The New York Sun.