Israel’s 60th anniversary has come and gone. So, too, has President George W. Bush’s final visit to the Middle East. Amidst the celebrations and the soul-searching, no meaningful breakthrough in the deadlocked Israeli-Palestinian negotiations is visible.

Looking back at 60 years of American involvement in the region, one can discern two scenarios in which the United States can bring the local players to an agreement. Absent these conditions, the US is ultimately powerless. The first scenario is when a real war threatens to spill over into a wider conflict, destabilizing the region and great power relations. At such times, resolute American steps can stop the fighting and impose a cease-fire, if not peace.

In 1973, at the end of the Yom Kippur War, Israel was poised to encircle the entire Egyptian Third Army in Sinai. Its troops were on the road to Cairo, threatening to inflict a major defeat on Egypt. Soviet intervention became a real threat. A few tough messages from President Richard Nixon stopped the Israelis in their tracks and enabled the Americans to start a lengthy process of de-escalation that led to a number of interim agreements.

Likewise, in 1982, during the invasion of Lebanon, Israeli troops were about to enter Muslim West Beirut after the pro-Israeli Lebanese President-elect Bashir Gemayel was assassinated allegedly by Syrian agents. This would probably have brought Syria into the war. A few tough calls from President Ronald Reagan to Prime Minister Menachem Begin prevented this.

During the first Gulf War in 1991, when Iraq fired 39 Scud missiles at Israeli civilian targets and US forces failed to stop the Iraqi attacks, Israel was set to strike Iraqi targets, which would have split the US-Arab anti-Iraq coalition. The US warned Israel not to get involved, and Israel was forced to comply.

In all these cases, American involvement was swift and focused on a clear aim, and compliance was verifiable within days, if not hours. In such dramatic situations, US power is at its greatest.

The other scenario is when the two sides have already engaged in bilateral peace talks, paid the domestic political price, and reached agreement on most issues, though some matters remain unresolved and threaten to derail the process. In such cases, America can step in and, by using both carrot and stick, make both sides go the extra mile.

After Anwar Sadat’s visit to Jerusalem in 1977, Israel and Egypt negotiated for a year and reached agreement on most issues: Peace, diplomatic relations, and full Israeli withdrawal from all occupied Egyptian territory in Sinai. At this point, President Jimmy Carter — who initially opposed the process — invited both sides to Camp David to hammer out a peace treaty.

In 1993, in secret bilateral negotiations in Norway (unknown to the Americans), Israel and the PLO reached an agreement about mutual recognition and the creation of a provisional Palestinian Autonomous Authority. Yet some issues remained unresolved. President Bill Clinton stepped in, and prevailed upon the two sides to work out their remaining disagreements.

When either of these two scenarios is lacking, American initiatives are stillborn.

This happened to Clinton at Camp David in 2000, and to Bush’s road map in 2003, when both sides agreed in principle to its general guidelines, but did little to implement them.

Absent local political will, and when confronted with a peace-making project that may take years to complete, the US is virtually powerless. It is extremely successful as a fire brigade or as a midwife, but not as an initiator. What applies to the US is even truer for the European Union, whose “soft power” is no match for its lack of local credibility.

The same dynamic can be seen elsewhere: For all its power, the US has failed to resolve the conflicts in Cyprus, Bosnia, or Kosovo. The Annan Plan failed in Cyprus because of one party’s opposition; progress now reflects internal political changes on the Greek Cypriot side. Similarly, if Belgrade will change its obstreperous position on Kosovo, this will be due to internal political changes in Serbia.

Recognizing the limits of US power doesn’t mean that America is irrelevant: It can stabilize a conflict, help bring about confidence-building measures, and negotiate interim agreements. But at the end of the day, in the case of Israel-Palestine, as in any conflict between two national movements, the key is in the hands of the local players. No national conflict has ever been solved by outside powers, however well intentioned they may be.