U.S. rejection of Iran deal would undermine U.S. - E.U. relations while strengthening positions of China and Russia
If the US Congress spoils the Iran deal, a difficult debate will take place among Europeans as to their options. Europe could succumb to economic pressure, align itself with Congress and renege on the deal. But at a time when European relations with Tehran have warmed, and in a situation where Congress has obstructed the deal without giving it a chance to succeed, Europeans are likely to sympathize with Iran and forcefully stand against the US legislature.
If the US Congress wrecks the deal, Europeans will need to provide Iran with a package that offers economic easing from EU sanctions on the condition that Iran curtails its nuclear program. They will also need to protect their companies from US secondary sanctions by exerting the type of political pressure used to resist the Clinton administration’s extra-territorial sanctions on Libya and Iran in the 1990s. And whether Europe aligns itself with an anti-deal US Congress or not, it will incur costs and have to prepare to deal with the consequences of another military confrontation in the Middle East.
As Obama correctly noted, if Congress rejects the Iran deal it is inconceivable that America’s partners in Europe would then say “we’ll just do what [Arkansas Republican Sen.] Tom Cotton has to say with respect to our geopolitical interests.” US members of Congress opposed to the deal must be alert that their threats against Europe, and insistence on reaching a fantasy deal, are troubling many of their allies. This risks undermining trans-Atlantic unity and ultimately Western leverage, while inadvertently strengthening China and Russia. It’s understandable that Congress may see itself as omnipotent on domestic issues, but it would be dangerous for it to take a similar stance with world powers regarding matters of global security.
If the U.S. congress rejects the nuclear deal with Iran, it will have multiple negative reprecussions for U.S. interests and security. The most likely impact of U.S. rejection of the deal will be a gradual collapse of the sanctions regime as our partners have no interest in reopening negotiations with Iran and are already starting to renew trade relations. Additionally, rejection of the deal will damage U.S. credibility as a global leader and its diplomatic capital for many years as the U.S. was critical in forming the consensus for the deal in the first place.