Ever since Sept. 11, 2001, whenever Americans seem especially polarized over a controversial issue, you hear pundits recall how united we’d became in the aftermath of that vicious attack. Why, they ask, can’t we be like that again?

A big part of the reason, frankly, is a lack of leadership at the top level. The tone set by President Obama and his team as they deal with world affairs hardly inspires confidence, either at home or abroad. And left unchecked, their lack of true resolve can lead to some very serious repercussions.

Take our situation with Iran. Some of the Heritage Foundation’s top experts on foreign policy recently published a short assessment of the deal the administration has been pursuing. They listed a number of shortcomings, but one sentence in particular jumped out at me:

“The emerging nuclear deal with Iran is likely to lead nervous countries in the region to seek their own nuclear weapons, fueling a cascade of nuclear proliferation that will undermine U.S. security interests in the volatile Middle East and provide Iran with even more resources to fund its many terrorist activities around the world.”

Why is that? Certainly, it has much to do with the details of the deal. But the main problem is that it’s not giving other countries what they seek more than anything. Regardless of its political ideology, the leadership of every country that’s not a complete basket case craves one thing above others: stability.

A business leader that I know in Hong Kong was stressing this to me recently. We don’t know, he was saying, with any degree of confidence, that your country is going to continue to ensure that the nuclear situation won’t get out of hand.

What does that lead to eventually? Other nations start seeking their own nuclear weapons. We wind up with more arms. More tension. It doesn’t take much imagination to realize that creating a bigger, dryer powder keg makes it more likely that a loose spark will lead to a level of hostilities no one wants to face.

And why? Because the administration is more concerned with scoring a diplomatic breakthrough with Iran than in protecting U.S. allies from a possible Iranian breakout. It’s more interested in the short-term political benefits of an agreement than in the long-term security goal of making sure the bad guys are safely contained and rendered incapable of hurting a lot of innocent people.

Even the administration knows this is a bad deal, which is why it’s being pursued as an executive agreement and not as a treaty. A treaty, after all, would have to be approved by a two-thirds majority in the Senate, and there’s little chance of that happening.

How could it? The deal as it stands now won’t arrest Iran’s nuclear weapons efforts. It simply slows them down for a while. Once the restrictions on uranium enrichment expire in 10 to 15 years, the Heritage experts note, Iran will be set to stage a true nuclear breakout.

The deal allows Iran to maintain more than 6,000 operational centrifuges for 10 years. At that point, it will be free to build a much bigger nuclear program than it has now. The deal also essentially accepts Iran’s “right” to enrich uranium, despite six U.N. Security Council resolutions that called for a halt to its enrichment efforts.

Furthermore, Iran doesn’t have to dismantle its nuclear infrastructure. No wonder U.S. allies are getting nervous. They can plainly see that this oh-so-wonderful deal is nothing more than a “cool your heels for a while” affair.

In short, it does little to promote stability. Our regional allies, including Israel, Egypt, Bahrain, Jordan, Saudi Arabia and the United Arab Emirates, are understandably concerned that any future nuclear deal between the United States and Iran will come at their expense.

“Speak softly and carry a big stick,” President Theodore Roosevelt famously advised. Sage words, but if anything supersedes a big stick, it’s stability. By failing to provide this, the Iran deal can only make the world a more dangerous place.