Two Israeli missile class warships sailed through Egypt’s Suez Canal into the Red Sea this week, some days after one of their nuclear submarines. The news barely blipped the media surface of the United States.

It should have raised a few questions: Will Israel really attack Iran? What does the law have to say to Israel - and to Egypt? Will the world act to prevent war?

The idea of an Israeli attack on Iran is almost unthinkable. It could devastate Iran and have repercussions beyond a counter-attack on Israel. Nuclear fallout could affect neighboring countries. Americans in the region and elsewhere could be vulnerable. Iran could close the Strait of Hormuz through which about 20% of world oil flows, perhaps felling a global economy already on its knees. As French president Nicolas Sarkozy said at the G8 summit, such a unilateral act would be an “absolute catastrophe.”

Barack Obama wants a diplomatic resolution of the standoff over Iran’s nuclear program, so perhaps all we are seeing is Israeli sabre-rattling. If this is all, it is still useful to Israel. Israeli strategists have openly said they prefer Mahmoud Ahmadinejad in power - his inflammatory rhetoric is more likely to keep Iran at loggerheads with the world - and an external threat strengthens Ahmadinejad against his reformist rivals. Israeli military maneuvers also reinforce Iran’s determination to seek a nuclear deterrent, thus keeping the country isolated. And it distracts attention from Israel’s relentless colonization program in the occupied Palestinian territories.

Yet an attack cannot be ruled out: Israel has been known to do the unthinkable. The world cannot afford to wait and see. The United States in particular needs to take more muscular action. The Obama administration does not have to expend political capital by taking Israel on by itself. It can make use of the protection provided by the United Nations and international law.

There’s plenty to work with: An Israel strike against Iran would be against the law. Any state’s use of force must be justified as self-defense; otherwise, it is a fundamental violation of the United Nations Charter. What’s more, International law expert Richard Falk says, even the threat to use force is unlawful.

Israel’s “threat diplomacy” is “explicitly prohibited by the Charter,” the American Jewish law professor explains, because the threat to use force can be as disruptive as the use of force itself. It constitutes a crime against peace, as it was defined at the Nuremburg Tribunal after World War II, becoming a principle of international law. It promotes an arms race and escalates tension.

Today, there are tensions indeed, and they evoke eerie echoes of the June 1967 war. The weeks before the war were full of military maneuvers and tough talk that culminated in the lightning Israeli attack on and victory over Egypt, Syria, and Jordan.

Israel knew full well that the Arabs did not intend war. The late premier Menachem Begin told the Israel National Defense College in 1982: “We must be honest with ourselves. We decided to attack [Nasser].” The military swagger provided the cover for Israel’s strike.

If the world doesn’t want to spend the next 42 years trying to unravel the consequences of another Israeli attack - this time against Iran - it must act fast.

First, countries must be careful not to be complicit in Israel’s “threat diplomacy.” So while Egypt has no right to block the passage of Israeli vessels through the Suez Canal, Falk refers to the concept of “innocent passage” in international law. Whether Israel’s deployment of its warships and nuclear submarines can be seen as innocent - given the threats it has been making - is a tricky question under international law. Egypt may well have a duty to the international community not to allow such passage. And if so, the international community must support it in this position.

Second, countries must lay down the law. Obama was quick to deflect Joe Biden’s claim that Israel, as a “sovereign nation” was entitled to decide on a strike against Iran. Obama underscored that America had “absolutely not” given Israel a green light. He even appeared to slap his vice president on the wrist by saying it was very important that his administration be as clear and “as consistent as it can be.”

But Obama did not go far enough. Biden’s remark is not just another unguided missile: It is not consistent with international law. No state, however sovereign, has the right to threaten world peace unless it is acting in self-defense or has a mandate from the United Nations Security Council.

This is what Biden should have said, what Obama must say, and what all countries, Egypt included, must uphold. Otherwise we will all pay a heavy price.

BlackCommentator.com Guest Commentator. Nadia Hijab, is a Senior Fellow at the Institute for Palestine Studies. This commentary was syndicated and distributed by Agence Global. The Institute has produced authoritative studies on Palestinian affairs and the Arab-Israeli conflict since 1963. Its flagship Journal of Palestine Studies is published by the University of California Press. Click here to contact Nadia Hijab.