Twelve years after the start of the war in Afghanistan, the United States is still trying to negotiate an exit. Nine years of war in Iraq did not prevent an Al-Qaida comeback in Fallujah and Ramadi, where U.S. troops engaged in fierce fighting and suffered significant losses.

With that context, it should be easy for Congress to wait just six months to see if the newly inked agreement between Iran and major world powers can avoid yet another major Mideast war, and instead peacefully resolve the global standoff over Iran’s potential nuclear weapons program.

Unfortunately, the U.S. Senate seems set on joining the House in voting to impose new sanctions on Iran. Doing so would likely not only unravel the deal, but also the global coalition that got Iran to the negotiating table in the first place. Instead, the Senate should heed President Obama’s plea that “now is the time to give diplomacy a chance to succeed.”

Obama has threatened to veto any new sanctions. But the Senate is reportedly coming close to a veto-proof majority. So the votes of Minnesota Sens. Amy Klobuchar and Al Franken are crucial. Both should vote against new sanctions in order to let the multilateral diplomatic process move forward.

Waiting to impose new sanctions would not reflect the administration’s naivete on Iran. It is well aware that the theocracy controlling the country is made up of irresponsible international actors. And it’s not just the nuclear issue: The State Department also lists long-standing concerns over Iran’s sponsorship of terrorism and human rights record. Iran has exacerbated the nihilistic violence in Syria by directly aiding the Assad regime. For understandable reasons, Israel and regional rivals like Saudi Arabia consider Iran an existential threat.

According to the White House, the six-month deal would require Iran to start eliminating its stockpile of higher levels of enriched uranium and dismantle some of its nuclear infrastructure. Iran would limit its enrichment capability by not installing or starting up additional centrifuges or using next-generation centrifuges. Iran’s existing program would be more accessible to inspectors. In exchange, a “modest” amount of sanction relief, reportedly up to $7 billion, would be granted.

The short-term agreement is not ideal. And reportedly even the president thinks prospects for a long-term agreement are about “50-50.” But a new sanctions bill, even if it is intended to not take effect until after the six-month interim agreement, could be interpreted by Iranian hard-liners as an excuse to abrogate the interim pact and push to accelerate Iran’s potential weapons capability. It might also weaken the world’s resolve to levy strict sanctions in Iran.

“Sanctions inevitably unravel,” said Barbara Slavin, a senior fellow at the Atlantic Council’s South Asian Center. Slavin, an expert on the nuclear issue, said that maximum leverage has been reached and that the global focus should be on Tehran — not Washington. “We don’t want to be the first to break this agreement. We want the onus to remain on the Iranians to implement this agreement. And that’s why new legislation would be so damaging. … The only reason these sanctions have been so successful is because they have been multinational.”

It would be irresponsible for Congress to undermine the multilateral coalition. If the interim deal is derailed, Congress should be prepared for a possible call for U.S. military action or to back an Israeli strike against Iranian facilities.

It’s worth noting that many of those most hawkish on Iran over its potential nuclear weapons program were dead set against a strike on Syria for its actual use of chemical weapons.

The leaders of the so-called P5+1 — the United States, Great Britain, France, Russia, China and Germany — should be commended for using sanctions as they were intended: to convince Iran that the cost of developing nuclear weapons was simply too high. Congress should let the process play out. As the post-9/11 era shows, it’s much easier to begin military conflicts than it is to end them.