Sanctions and sabotage have not stopped them. Neither have threats nor United Nations resolutions. Iran's leaders say they'll never give up their nuclear program, and evidence shows the Iranians are closer than ever before to acquiring the bomb.
So how would a nuclear-armed Iran change the face of the Middle East and the world?
According to reports, Iran already has enough enriched uranium to produce at least four nuclear bombs.
And unless something changes, it appears the writing is on the wall for Iran's neighbors.
"In the end, I would argue that Saudi Arabia, which is the most Sunni, most Wahhabi -- which is the most extreme of the Sunnis -- is in more danger than America or Israel or Europe or anybody else," Harold Rhode, a senior advisor to the Hudson Institute, told CBN News.
Rhode, a former foreign affairs specialist at the Pentagon, said nuclear weapons would allow Iran to dominate its neighbors and set the global price of oil.
"The Saudis and other people who are supplying the world with oil and gas would have to kowtow to the dictates of this tyrannical regime in Tehran," he predicted.
Iranian leaders are also reaching out to the radical forces that have gained power due to the so-called Arab Spring. They're calling on the Muslim world to unite for a final showdown with Israel and the West.
A nuclear arsenal could be the galvanizing force that does just that.
An Iranian nuclear umbrella could also protect the terror groups Hamas in Gaza and Hezbollah in southern Lebanon.
Fear of nuclear retaliation might force Israel to think twice before responding to attacks by these Iranian proxies.
But Iran would use the bomb to flex its muscle far beyond the Middle East. The Iranians now have missiles that can reach most of Europe and they're working on ones that can reach the United States as well. With their cities in the crosshairs, Western leaders could be forced to take a much softer tone toward Tehran.
Some have argued that Iran only wants to have nuclear weapons to deter its enemies -- that it would never actually use them.
Yet Iranian leaders say the return of their Islamic messiah -- known as the Mahdi, or Twelfth Imam -- is drawing near. In their view, using nuclear weapons against Israel or the West could hasten his appearance.
"He will come back and save them. So an attack and a conflagration is an incentive," Rhode explained.
Iran expert Dr. Michael Ledeen, a freedom scholar with the Foundation for Defense of Democracies, said when Iranian leaders threaten to destroy America and Israel, we should take them at their word.
"Obviously, their nuclear program is closely related to their messianic vision," he said.
He notes that the West ignored the statements of Hitler and other tyrants during the 20th century and paid a heavy price.
"Over and over and over again we said, 'Nah, they can't possibly mean these things.' But they meant it and they did it. So any prudent leader has to act under the assumption that they mean it and they'll do it," Leeden said.
Erick Stakelbeck is the terrorism analyst at CBN News.