A prestigious bipartisan group of former senators is urging the US to prepare serious sanctions to use against Iran and make use of the threat of military force to prevent Teheran from building a nuclear weapon The authors of the report "Meeting the Challenge: Time is Running Out," which was released this week, argued against giving diplomacy too much time and rejected the notion that Iran should be given some leeway in the wake of the chaotic presidential elections, as some have contended would allow the opposition more time to prevail. "Deferring any action until Iran's internal political situation stabilizes ignores a simple truth: The centrifuges at [the] Natanz [nuclear plant] will continue spinning, regardless of political developments in Teheran," wrote former senators Daniel Coats, Charles Robb and retired general Charles Wald of the Bipartisan Policy Center, an organization begun by former Senate majority leaders including George Mitchell and Bob Dole. If talks with Iran do "not soon yield tangible results, Washington should begin serious preparations both for 'crippling sanctions' and the eventuality that even such measures will not thwart Teheran's nuclear ambitions." The experts warned that if "biting sanctions" weren't effective, "the White House will have to begin serious consideration of the option of an American-led military strike against Iranian nuclear facilities," which they maintained was key to convincing not only Iran but also regional allies that the US was serious about preventing an Iranian nuclear bomb. Otherwise, they wrote, the risk of a unilateral Israeli attack would increase, while with such overt planning, other actors such as Germany and China were more likely to get serious about sanctions. "We believe only the credible threat of a US military strike will make a peaceful resolution of the crisis possible," the authors contended. They also assessed that an Israeli attack would carry with it greater risk than an attack by the United States: "We anticipate an Israeli strike would be of very short duration, less effective than a US strike, would lead to larger international condemnations, even from some countries that might privately welcome it, and - because the timing would be unexpected - could provoke more effective Iranian reprisals against US regional allies." They added, "In the event of an Israeli attack, we do not believe that the Islamic Republic would limit its retaliation to Israel." The findings were a follow-up to a report the group wrote in September 2008, and were precipitated by the advances in Iran's nuclear program, as well as political developments. Some of the original contributors - most notably Dennis Ross, who is now a key White House architect of Iran policy - did not take part in the updated version because they had since joined the Obama administration. The recent study, though, noted that the original report had referred to the prospect of military action as "a last resort." The new assessment added that "the prospect of military action needs to be taken more seriously in Washington and Teheran." It indicated concern that while "President [Barack] Obama has clearly left it on the table as an option, the conflicting messages coming from the administration on this subject would have given the Iranians reason to doubt the strategy would ever be implemented." The report also berated the United States as a whole for not undertaking a "serious public discussion" about the Iranian nuclear challenge and stressed that, given the dire threat, "it's incumbent on US political leadership to make hard and even unpopular choices."