By all rights, President Obama should be having a lousy 2015. After losing the Senate to Republicans in the 2014 midterms, the political punditry was writing off the remainder of Obama's second term as a wash: At best, he would finally get to put some mileage on that veto pen.

About a month later, Obama and Cuban President Raul Castro announced an unexpected thawing of U.S.-Cuban relations, ending more than 50 years of overt and covert animosity between the U.S. and its small communist neighbor. And on Tuesday, Obama's negotiators reached a landmark agreement to throttle Iran's capacity to build a nuclear weapon for at least 15 years. Since November, Obama has put the U.S. on speaking terms with two of its biggest global foes of the modern era.

Obama has scored other victories over the past eight months — winning fast-track trade promotion authority for the ambitious Trans-Pacific Partnership, for example, and being on the right side of Supreme Court rulings in favor of ObamaCare and gay marriage — but it is the Iran deal that has finally justified the Norwegian Nobel Committee's preposterously premature decision to award Obama the 2009 Nobel Peace Prize.

In making Obama a Nobel laureate, the committee cited the president's "vision of and work for a world without nuclear weapons." Until Monday, Obama's record on nuclear disarmament was at best a mixed bag.

On the one hand, he won a promising New START nuke-reduction treaty with Russia in 2010. On the other hand, North Korea's nuclear program has pushed forward and the post-New START modernization of U.S. and Russian nuclear missiles prompted the Bulletin of the Atomic Scientist to move its Doomsday Clock up two minutes this year, putting the planet and humanity just three minutes away from destruction.

In preventing Iran from developing a nuclear weapon, though — something the White House says the new deal accomplishes — the chances of a nuclear inferno in the volatile Middle East have been dramatically lowered, notching a big win for nuclear nonproliferation.

In 2009, the Nobel Committee didn't only focus on nukes, though: It also lauded Obama's "extraordinary efforts to strengthen international diplomacy and cooperation between peoples." The Iran deal checks that box, too. Obama's Nobel citation continues:

Obama has as president created a new climate in international politics. Multilateral diplomacy has regained a central position, with emphasis on the role that the United Nations and other international institutions can play. Dialogue and negotiations are preferred as instruments for resolving even the most difficult international conflicts. [Norwegian Nobel Committee]

No matter what you think of the Iran deal, it is certainly a triumph of multilateral diplomacy. The main players in the long, fragile negotiations may have been Tehran and Washington, but five other powerful nations — with their own interests and agendas — had to contribute to and sign off on the accord, also. Getting Iran, Russia, China, France, Germany, Britain, and the U.S. to agree on concrete steps to gradually swap Iran's nuclear capabilities for sanctions relief is a masterwork of diplomacy and a masterpiece of the long game.

There's always the chance that the Iran deal won't work, or may even backfire. If Iran's regional archenemy Saudi Arabia takes the agreement as license to go nuclear, for example, all bets are off. The truth is, we won't know whether the agreement is going to work as Obama intends until long after Obama is out of office.

But the Norwegians didn't give Obama a Nobel Peace Prize for saving the world. They awarded him one of the world's top honors for trying to build peace through international cooperation, staking their reputation on Obama taking diplomatic, nonviolent action to resolve "even the most difficult international conflicts."

There have been times that looked like a sucker's bet. After Tuesday's landmark deal, the Norwegian Nobel Committee can breathe a sign of relief. Obama's earned his big gold coin.