As a site dedicated to helping investors, we don't usually spend a lot of time covering world news. We assume you can watch your local television news, or click on Yahoo or CNN any time you'd like in order to be kept up to speed on what's happening around the globe. So, why are we running a Top Story on the President's challenge of Iran's nuclear ambitions? In short, because the words "geopolitical tensions" have a tendency to impact the stock market from time to time.

The question of whether or not Iran desires to join "the club" (as in the group of nations possessing nuclear weapons) probably isn't going to have an impact on the earnings of GE, IBM, Intel, or Bank of America this quarter or even next. But, one thing is for sure in the business of managing money in the markets; the stock market HATES uncertainty. And if there is one thing that causes uncertainty it is "geopolitical tensions" – especially when it comes to Iran and its neighbors.

Thus, one of the issues that may have pushed stocks lower on Thursday and Friday was the fact that President Obama, with a little help from his friends in Europe, is calling out Iran on the issue of nuclear weapons.

The President said in a speech to the G-20 meeting in Pittsburgh Friday, "Iran is on notice that when we meet with them on Oct. 1 they are going to have to come clean and they are going to have to make a choice between international isolation and giving up any aspirations to becoming a nuclear power," he said. "If they refuse to give ground, they will stay on a path that is going to lead to confrontation."

The speech followed the dramatic morning announcement about the discovery of a secret Iranian nuclear facility and demands for access to the facility. Obama said, "Iran is breaking rules that all nations must follow. The size and configuration of this facility is inconsistent with a peaceful program."

In typical fashion, the Iranian response was one of denial. In short, Iranian President Mahmoud Ahmadinejad said his country had done nothing wrong and Obama would regret his accusations.

At his own press conference, Ahmadinejad was dodgy on the question about whether Iran had sufficient enriched uranium to manufacture a nuclear weapon but said the plant wouldn't be operational for 18 months. He went on to say that such armaments "are against humanity, they are inhumane," and he said anyone who pursues them "is retarded politically."

The deadline for Iran to allow U.N. inspectors appears to be October 1st. And while Obama prefers a diplomatic approach, he said, "When we find that diplomacy does not work, we will be in a much stronger position to, for example, apply sanctions that have bite," He then cautioned, "That's not the preferred course of action. I would love nothing more than to see Iran choose the responsible path."

During his campaign for President, Obama was often critical of then-President Bush for acting unilaterally and pledged that if elected, he would work toward building a coalition of our allies in times such as these. Friday, Obama called the international response to Iran's nuclear ambitions "an unprecedented show of unity."

The Europeans were talking tough on the issue as well Friday. British Prime Minister Gordon Brown, said "We will not let this matter rest," and accused Iran of "serial deception."

French President Nicolas Sarkozy said Iran has until December to comply with demands for a fuller accounting of its program or face tough new sanctions.

Even the Russians seem to be on board with threatening Iran to do the right thing. President Dmitry Medvedev urged Iran to cooperate and "demonstrate its good intentions" at the Oct. 1 meeting and in allowing inspections. "We call on Iran to show maximum cooperation with the IAEA on this issue," Medvedev said.

So there you have it. Regardless of whether you find yourself in the bull or bear camp at the moment, this is the big geopolitical problem that could be a fly in the ointment of the bull market in stocks. But for now at least, it appears to be something that isn't being given much ink in the financial press.