The Obama administration and other opponents of the pending Senate bill that would tighten sanctions on Iran in the event the current nuclear negotiations fail, claim it would blow up the diplomatic process. This makes no sense because the Iranians are the principal beneficiaries of the talks and have far more to lose than the West if the talks collapse because they would then lose the  chance to get all the sanctions lifted. But the administration and its defenders also claim the bill is unnecessary since the current sanctions are still working (despite being weakened during the interim accord) and can easily be strengthened in the event that Washington concedes that the process has failed at the expiration of the six-month period for negotiations, which begins today.

But the problem with that argument, as the New York Times reported on Friday, is that Iran is open for international business now. While there have been signs indicating that Iran’s economy is already recovering from the impact of sanctions, the interim accord has led to a parade of European businessmen trooping to Tehran to lay the groundwork for what they see as the impending collapse of the restrictions on transactions with the Islamist regime. Indeed, according to the Times one of the busiest people in the Iranian capital is Hossein Sheikholeslami, the former terrorist (he was one of the “students” responsible for holding American diplomats hostage in 1979) assigned to fielding offers from nations including Germany, Italy, and Finland which, despite their nominal allegiance to the U.S.-led sanctions coalition, are champing at the bit to get their bids in now for contracts to do business in Iran.

Seen in that light, we won’t have to wait until July to know whether the latest P5+1 with Iran talks will succeed. If the sanctions are coming apart at the seams today, then the interim accord has already failed.

As critics of the interim accord signed in Geneva in November said at the time, the decision by the Obama administration to begin the process of loosening sanctions just at the moment when they appeared most effective in their goal of forcing Iran to end its nuclear program was nothing short of a fatal mistake. Though the president has mocked the idea that the new sanctions being considered by the Senate would strengthen his hand in the talks, his decision to grant the Iranians significant relief from the earlier sanctions has already begun the process by which the entire edifice of economic restrictions is virtually in shambles.

As the Times story illustrates, the actions of European nations that were unenthusiastic about sanctions from the start (which could also be said of the Obama administration since it opposed the current tough sanctions when Congress debated their adoption) are allowing the Iranians to claim that the sanctions regime is tottering. This will strengthen Tehran’s hand in negotiations since it may reasonably conclude the U.S. can’t count on international support for renewed sanctions if, as is more than likely, the Iranians refuse to dismantle or even substantially degrade their nuclear program in the coming talks.

Nor is the interest in resuming business with the Islamist tyrants confined to a few outliers or even only Europeans:

In the first two weeks of the year, Iran welcomed more delegations from Europe than in all of 2013.

“The Europeans are waiting in line to come here,” said Mr. Sheikholeslami, the international affairs adviser to the head of Iran’s Parliament, Ali Larijani, who has been receiving many of the high-profile visitors. “They are coming to seek benefits and to get ahead of their international rivals.”

Italy’s foreign minister, Emma Bonino, has been here, as has a former British foreign minister, Jack Straw, in his capacity as the head of the Iran-Britain Friendship Committee.

The prime ministers of Italy and Poland have also scheduled visits. Trade delegations from Ireland, Italy and France are expected in coming weeks.

American companies have shown some interest, of course. In September the head of President Hassan Rouhani’s office, the former director of the Iranian Chamber of Commerce, Mohammad Nahavandian, held a closed-door meeting with leading chief executives in New York. In March, an Iranian investment company is organizing a $15,000-a-ticket seminar in New York on business opportunities in Iran.

President Obama and others who claim more sanctions can only mean war say the only path to peace runs through the diplomatic process and that it must be given more time to succeed. But the boomtown atmosphere in Tehran that has kept Sheikholeslami hopping is proof that the real choice is not between more sanctions and diplomacy. Without a law on the books that will mandate a complete economic embargo of Iran if the diplomats fail to produce a deal that ends the Iranian nuclear threat, Tehran can confidently assume it has nothing to lose from more delaying tactics and a refusal to give up its nuclear dreams.

The administration has also further undermined its own leverage with Iran by demonstrating its eagerness to cooperate with Tehran on the conflicts in Syria and Iraq. That rightly scares American allies in the region and gives the impression that President Obama is more interested in fostering détente with Iran than in making good on his campaign promises to force it to give up its nuclear program. With “open for business” signs going up in Tehran as European delegations arrive to renew ties, rather than denouncing the sanctions bill, the administration should be embracing it as its last best hope to convince the Iranians that they have no other option but to negotiate the surrender of their nuclear project.