Thirty-six retired U.S. generals and admirals released an open letter supporting the Iran nuclear deal, urging Congress to do the same.

"The international deal blocks the potential pathways to a nuclear bomb, provides for intrusive verification, and strengthens American national security," the officers opined in the letter, according to Haaretz.

The letter came as Secretary of State John F. Kerry said U.S. allies were "going to look at us and laugh" if the United States were to abandon the deal.

"It's not going to happen overnight. But I'm telling you, there's a huge antipathy out there" to U.S. leadership, Kerry said. "There's a big bloc out there, folks, that isn't just sitting around waiting for the United States to tell them what to do." Kerry was referring to efforts by Russia and China to join forces with nonaligned powers in a public question-and-answer session at Reuters.

"When I hear a senator, a congressman stand up and say 'We should get a better deal' - that is not going to happen. If everybody thinks 'Oh, no, we're just tough. . . . we can force people. . . . America is strong enough, our banks are tough enough, we can just bring the hammer down and force people to do what we want to do,'" Kerry said, according to The Washington Post.

In the letter, the retired military officials called the deal "the most effective means currently available to prevent Iran from obtaining a nuclear weapon" according to The Washington Times.

Marine Gen. James Cartwright, former Vice Chairman of the Joint Chiefs of Staff; Joseph P. Hoar, former head of the U.S. Central Command; and Gen. Merrill McPeak and Gen. Lloyd W. Newton of the Air Force are among signatories to the letter which includes other retired general and flag officers from every branch of service.

"There is no better option to prevent an Iranian nuclear weapon," the letter said. "Military action would be less effective than the deal, assuming it is fully implemented. If the Iranians cheat, our advanced technology, intelligence and the inspections will reveal it, and U.S. military options remain on the table. And if the deal is rejected by America the Iranians could have a nuclear weapon within a year. The choice is that stark."