When the Obama administration set up the toughest sanctions regime ever imposed on Iran, its goal was to force Tehran to the bargaining table. It aimed to address the country's suspect nuclear program by diplomacy rather than war.

The sanctions worked, contrary to widespread predictions. Under heavy economic pressure, Iran's new president, Hassan Rouhani, initiated nuclear talks in Geneva.

Yet rather than give talks a chance, U.S. legislators from both parties - urged on by Israeli Prime Minister Benjamin Netanyahu - want to impose even stiffer sanctions soon. Never mind that such a move would probably derail the talks, as well as any hope of curbing Iran's program by diplomatic means.

I can understand Netanyahu's thinking: He distrusts Tehran and wants President Obama to back an Israeli military strike on its nuclear sites. But I can't grasp the "thinking" in Congress. Are the sanctions hawks really ready to push America into another unnecessary Mideast war?

The hawks argue that if strong economic curbs pushed the Iranians into talks, then harsher punishment will make them give up their nuclear program. But when it comes to Iran, that kind of strategy has failed badly in the past.

One has only to recall the period after 9/11, when Tehran cooperated closely with Washington in going after their common Taliban enemy in Afghanistan. At that time, U.S.-Iran talks in Geneva seemed set to deliver further cooperation. But after George W. Bush named Iran part of the "axis of evil" in January 2002, it withdrew from the talks.

According to Ryan Crocker, who was then the U.S. negotiator in Geneva (and later ambassador to Afghanistan), the Iranians concluded from Bush's proclamation that America was implacably hostile. A ratcheting up of sanctions now would probably lead Iran to the same conclusion. (Iran's current foreign minister and nuclear negotiator, Mohammad Javad Zarif, happens to be the man with whom Crocker conducted those promising talks.)

Another factor propelling the sanctions hawks is the claim, also promoted by Netanyahu, that the Obama team was about to give away the store in the initial negotiations, including a huge amount of sanctions relief. "Bad deal!" thundered Israeli officials.

Yet there was no final deal in play, only an interim proposal under which the Iranians would have frozen most of their nuclear program and opened it to more vigorous inspections while talks continued on a final agreement. The reason for an interim accord - and it's a good one - is to ensure that Iran would not be free to make more nuclear progress during the months of negotiations that would be required for a comprehensive pact. This first step would provide time and space to test whether Iran is serious.

The interim accord is still being negotiated between Iran and the "P5+1": the five permanent U.N. Security Council members - France, Britain, Russia, China, and the United States - plus Germany; a second round of talks is set for Wednesday. France apparently persuaded the others to toughen a couple of provisions that Tehran has not yet agreed to. Stay tuned.

But - and this is important - the sanctions relief offered as part of the interim deal was modest, probably permitting the release of some frozen Iranian assets. That wouldn't, as critics claim, undermine the core sanctions on oil and banking, which have driven Iran to the table. Nor are investors likely to go rushing back to Tehran to sign contracts.

"Businessmen will be hesitant because the sanctions are still in place," said Robert Einhorn, a senior fellow at the Brookings Institution and a former top State Department adviser on nuclear issues. "Banks are very conservative, and financial sanctions still exist."

So, again I ask, why has there been such a rush in Congress to ratchet up sanctions?

Clearly the Israeli government's strong lobbying effort has had an impact. To quote one of Israel's leading journalists, Haaretz's Chemi Shalev: "The ferocity of Netanyahu's rage [at reports of the interim deal], accompanied as it was by a volley of protests and insults hurled by many Israeli politicians and commentators, astonished many administration officials in Washington and surprised some of its detractors as well."

Yet U.S. legislators should pay equal attention to the observations of former Israeli military intelligence chief Amos Yadlin. He argues that an agreement that decreases the chances of Iran's reaching the breakout stage - the point where it could produce a weapon in short order - would be far less risky than a military strike. Yadlin says Israel should focus on the substance and details of a final accord "even if Iran doesn't accept all of the prime minister's terms." In other words, try to make talks work rather than derail them.

As for America's sanctions hawks, they should focus first on U.S. interests, which would be best served by a deal that sharply limits Iran's nuclear program and makes it highly transparent. If talks drag on endlessly with no progress, Congress can consider additional sanctions. It makes no strategic sense to pursue them now.