Since the Iran nuclear agreement was announced last week, a rancorous debate has erupted over whether it's a good deal.

Supporters have hailed it as a landmark accord that promises to end Iran's atomic weapons program and encourage Tehran toward a more constructive future.

Critics blasted it as an historic mistake that doesn't indefinitely halt Iran's drive for a nuclear bomb and that funds from sanctions relief will allow it to boost its legitimacy while also further destabilizing an already volatile region. No deal, these critics say, is better than this deal.

That's disingenuous at best. Without a deal, Iran — which suspended its bomb program 20 months ago to enter negotiations — would be unchecked in quickly finishing the project: Iran would have a nuclear device, by far the worst possible outcome for the region.

Counter-proliferation experts, however, argue that if the conditions in the 159-page document are rigorously implemented on Tehran, the country's nuclear weapons program would be stalled for at least a decade.

If Iran complies, then the deal will be a success, giving the international community time to convince Tehran it has more to gain by changing its inflammatory behavior than by remaining on its current provocative course.

Indeed, Hassan Rouhani was elected by Iranians to help return the nation to the international fold, and once the population tastes sanctions relief, it will be reluctant to return to austerity. That said, the Revolutionary Guard — which answers to the nation's supreme leader, Ayatollah Ali Khamenei — remains enormously powerful politically and economically.

If, however, Tehran cheats or walks away, then the international community will be justified in responding with all means at its disposal, ranging from renewed sanctions to more extreme measures.

While the "Joint Comprehensive Plan of Action" could have been tougher on Iran, it is the only deal on the table. Painstakingly negotiated by six world powers over nearly two years, changing it now would be impossible, so making it work will be key.

The international community agreed to embrace punishing sanctions proposed by the United States to press Iran into accepting a diplomatic solution that would trade sanctions relief for its nuclear bomb program. The goal wasn't, as critics now suggest, to change Iran's vast array of flaws and dangerous strategic behavior that puts it at continuous odds with its neighbors.

If Congress kills the deal or significantly alters its terms, America would be blamed for the accord's failure and draw the ire of nations that joined the United States in hammering out an exhaustive pact only to see it crumble. The strong sanctions alliance would unravel and Iran would revive its bomb effort — and Washington's prestige and ability to marshal a global response to Tehran's renewed weapons push would be diminished.

World leaders rightly agree that preventing a nuclear-armed Iran is vital, but it is a goal that can be achieved in only two ways: through sanctions, sustained diplomacy and incentives; or armed confrontation. The former is preferable to the latter, which must remain an option but a tool of last resort.

Those that negotiated this deal must now rigorously enforce it, rewarding Iran for progress and punishing it for failure.

They, along with nations in the region, must maintain pressure on Iran to more broadly change its provocative behavior.

Here, the international community will face its most difficult diplomatic challenge — to change Iran's behavior without driving Tehran to opt for a bomb even if it means living with more domestic economic pain.