By Larry Korb

In his decision to oppose the nuclear deal that six of the world's major powers negotiated with Iran, Sen. Charles Schumer (D., N.Y.) echoed a number of the points that critics of the deal have continuously made.

Namely, a lack of anytime, anywhere inspections; the 24-day delay in inspecting non-declared sites; that the deal lasts only 10 years; that Iran cannot be trusted and will use the money it receives from sanctions relief to pursue harmful military and terrorist actions; and that if we go back to the negotiations, we could get a better deal.

But the senator adds a surprising new concern: We cannot trust our European allies to ensure that the deal will be correctly implemented.

While those who oppose the deal have the right to voice their concern, we would not be at the cusp of resolving the Iranian nuclear issue without our European allies. So why say they would hamper the implementation?

As the senator accurately notes, the deal needs a majority of the P5+1 countries (the United States, Germany, France, the United Kingdom, China, and Russia) that negotiated with Iran to demand inspections in non-declared sites, or to bring about a partial snapback of sanctions if Iran violates the terms of the agreement. Because the United States cannot make this happen unilaterally, we would need the support of our European allies.

But according to Schumer, "once the Europeans become entangled in lucrative economic relations with Iran, they may well be inclined not to rock the boat by voting to allow inspections." Schumer worries that the Europeans "may not comply" because they believe that snapped-back sanctions are "too severe a punishment."

While increased trade with Europe is certainly one carrot for Iranian compliance, the threat to the fragile Iranian economy of losing that trade is a mighty big stick.

Schumer overlooks the reality that Europeans have already forgone lucrative trade with Iran by joining and enforcing stringent economic sanctions. His lack of faith in our European allies to hold the line if Iran cheats is ironic, as it was the European and international commitment to making sure that Iran never gets a nuclear weapon that gave the sanctions teeth in the first place. In particular, the 2012 European sanctions on Iran's oil, shipping, and banking sectors were critical in bringing Iran to the negotiating table.

Ironically, at the same time that Schumer was raising concerns about our European allies, the ambassadors of the other members of the P5+1 addressed these concerns on Capitol Hill. Our European allies (and Russia and China) pointed out that not only do they support the deal and feel it makes Israel safer, but they also made it clear that if Congress does not approve this deal, there is not only no chance of getting a better deal, but the sanctions will fall apart, international unity on Iran will be destroyed, and the credibility of the United States in the world will be fundamentally eroded.

Schumer's colleague Sen. Kirsten Gillibrand (D., N.Y.) alluded to the meeting in coming out in support of the deal. According to her, "when I questioned the ambassadors of our P5+1 allies, it also became clear that if we reject this deal, going back to the negotiating table is not an option."

Schumer, on the other hand, believes that it is better to keep U.S. sanctions in place, strengthen them, enforce secondary sanctions on other nations, and pursue the already-trodden path of diplomacy once more. But he does not tell us what happens when these "untrustworthy" Europeans will not join us, as they have for the last five years, or what it would mean for our relations with our European allies as we attempt to deal with issues like the Russian incursion into Ukraine or the threats from ISIS and al-Qaeda offshoots in the Middle East.

By saying that he does not trust the intentions of some of our closest allies, Schumer is arguing that the United States must go it alone - a death knell for diplomacy as a way to tackle the crises of the world.

Larry Korb is a senior fellow at the Center for American Progress and a former assistant secretary of defense during the first Reagan administration.