World attention has rightly focused on Iran's harsh post-election crackdown, which illustrates the regime's true nature and the threat posed to the international community were it to possess nuclear weapons. As the political struggle inside Iran continues, the regime is pressing ahead with its nuclear program and rebuffing U.S. and European entreaties to enter serious talks. Indeed, Tehran has publicly mocked President Obama's outreach efforts. The United States will need to impose much tougher sanctions if Iran continues to violate U.N. Security Council resolutions and defy the international community.

Iran's violent crackdown highlights the serious threat this regime would pose if it possessed nuclear weapons.

• The repression of the protestors shows the true nature of the Iranian regime: a theocratic dictatorship that is not only the leading sponsor of international terrorism but represses its own people as they seek to voice their right to free speech.
  
  
• The Iranian regime continues to press ahead with its nuclear program amid the brutal internal crackdown. Possessing a nuclear weapons capability would embolden the regime, allowing it not only to continue to repress its own people but extend its influence throughout the region as part of its hegemonic ambitions.
  
  
• Armed with nuclear weapons, this oppressive regime would also feel stronger in carrying out its radical foreign policy agenda of undermining U.S. peace efforts in the region through support of terrorist groups Hamas and Hizballah, Shiite terrorists in Iraq and the Taliban in Afghanistan.
  
  
• Iran's acquisition of nuclear weapons also would likely touch off a regional nuclear arms race. Indeed, many Arab states have expressed new interest in "peaceful" nuclear programs as Iran continues its nuclear weapons pursuit.
  
  
• Once Iran possesses nuclear weapons, the regime, or rogue elements within it, could share this technology with anti-American terrorist groups to carry out attacks against U.S. interests worldwide.

Iran continues to advance its nuclear weapons program as it implements a violent repression of its own citizens.

• Iran increased the number of installed centrifuges in its Natanz enrichment facility by 30 percent between February and May 2009 to more than 7,000, according to the latest report by the International Atomic Energy Agency (IAEA). This number, according to experts, is enough to produce sufficient highly enriched uranium for up to two nuclear bombs a year.
  
  
• Iran has now produced nearly 3,000 pounds of low enriched uranium that-if further enriched to a weapons-grade level-is more than sufficient for one first-generation nuclear device.
  
  
• Within several months, Iran could raise the enrichment level of its uranium stockpile to weapons-grade using its existing centrifuges.
  
  
• The IAEA also reported that Iran is continuing its work testing more advanced centrifuge designs in order to reach its ultimate goal of 54,000 operational centrifuges and an industrial enrichment capability.

Iran has completely rejected U.S. outreach efforts about its nuclear program and other issues.

• President Obama has taken a number of steps to reach out to the Iranians, including taping a video greeting to mark Iran's new year, sending a private letter to Iran's Supreme Leader, inviting Iranian diplomats to July 4th celebrations at embassies around the world and acknowledging the U.S. role in ousting an elected prime minister, Mohammed Mosaddegh, in 1953.
  
  
• The president also reached out to Iran in his Cairo speech, saying: "There will be many issues to discuss between our two countries, and we are willing to move forward without preconditions on the basis of mutual respect."
  
  
• Iran's Supreme Leader Ali Khamenei and Iranian President Mahmoud Ahmadinejad have mocked and dismissed U.S. outreach efforts and said the nuclear issue is "closed."
  
  
• To distract attention from its internal crackdown and illicit nuclear program, the regime has falsely blamed the United States, Britain and Israel for fomenting the opposition protests.

As the United States evaluates its Iran strategy, tough sanctions can help persuade Iran to end its nuclear weapons pursuit.

• Tehran must not misconstrue U.S. engagement efforts as a reward for its continuing intransigence. Efforts to engage need to be backed by the threat of tougher sanctions to encourage the regime to enter negotiations and make clear the future Iran faces if it abuses America's genuine desire for better relations.
  
  
• To increase the negotiating leverage on Iran, the United States should work with its allies today on spelling out additional tough sanctions that will be imposed on Iran if talks are not successful.  Among such sanctions are:
  
  
  
  • An international diplomatic effort to prohibit the sale and export to Iran of refined petroleum products. With Iran forced to import up to 40 percent of its gasoline and diesel, limiting the country's access to such products would have a dramatic economic effect and could force the regime to change course.
    
    
  • Sanctioning Iran's Central Bank and any banks that continue to conduct transactions with sanctioned Iranian entities, and companies doing business with Iran's Islamic Revolutionary Guard Corps, as a means of enhancing pressure on Iran's regime.
    
    
  • The United States could also implement current law and sanction foreign companies investing more than $20 million per year in Iran's petroleum sector.   As senators, both Obama and Secretary of State Clinton voted to enact this legislation.