Here are some more detailed remarks from him:
The world must work to stop Iran’s uranium enrichment program and prevent Iran from acquiring nuclear weapons. It is far too dangerous to have nuclear weapons in the hands of a radical theocracy. And while we should take no option, including military action, off the table, sustained and aggressive diplomacy combined with tough sanctions should be our primary means to prevent Iran from building nuclear weapons.
Iranian nuclear weapons would destabilize the region and could set off a new arms race. Some nations in the region, such as Egypt, Saudi Arabia and Turkey, could fall away from restraint and rush into a nuclear contest that could fuel greater instability in the region that’s not just bad for the Middle East, but bad for the world, making it a vastly more dangerous and unpredictable place. Other nations would feel great pressure to accommodate Iranian demands. Terrorist groups with Iran’s backing would feel emboldened to act even more brazenly under an Iranian nuclear umbrella. And as the A.Q. Kahn network in Pakistan demonstrated, Iran could spread this technology around the world.
To prevent this worst-case scenario, we need the United States to lead tough-minded diplomacy.
This includes direct engagement with Iran similar to the meetings we conducted with the Soviets at the height of the Cold War, laying out in clear terms our principles and interests. Tough-minded diplomacy would include real leverage through stronger sanctions. It would mean more determined U.S diplomacy at the United Nations. It would mean harnessing the collective power of our friends in Europe who are Iran’s major trading partners. It would mean a cooperative strategy with Gulf States who supply Iran with much of the energy resources it needs. It would mean unifying those states to recognize the threat of Iran and increase pressure on Iran to suspend uranium enrichment. It would mean full implementation of U.S. sanctions laws. And over the long term, it would mean a focused approach from us to finally end the tyranny of oil, and develop our own alternative sources of energy to drive the price of oil down.
We must also persuade other nations such as Saudi Arabia to recognize common interests with Israel in dealing with Iran. We should stress to the Egyptians that they help the Iranians and do themselves no favors by failing to adequately prevent the smuggling of weapons and cash by Iran into Gaza.
The United States leverage is strengthened when we have many nations with us. It puts us in a place where sanctions could actually have a profound impact on Iran’s economy. Iran is highly dependent on imports and foreign investment, credit and technology. And an environment where our allies see that these types of investments in Iran are not in the world’s best interests, could help bring Iran to the table.
http://obama.senate.gov/speech/070302-aipac_policy_fo/He explains it a lot better than I can!