On Thursday, Mohamed ElBaradei, the head of the IAEA, said that efforts to investigate Iran's nuclear capabilities had "effectively reached a dead end." In the past, ElBaradei had privately spoken about Iran's refusal to answer the IAEA's questions about weapons but had stopped short of rebuking the country for fearing of halting any improvements in negotiations.
Last week, Iranian Foreign Minister Manouchehr Mottaki denied a P5+1 proposal in which Iran would send its low-enriched (3%) uranium to other countries for further enrichment. Instead, Mottaki said he would consider an exxhange of uranium for nuclear fuel inside Iran. However, Mottaki did not agree to any exchange. Some contend that this is a hesitation tactic used to buy time and test the seriousness of the international community's threats of consequences. The consequences, which in this case are sanctions, may not be as effective as the P5+1 nations may hope. In order for sanctions to work, the target country must be economically dependent on the countries issuing the sanctions, the pain inflicted will be significant enough to cause change, and that the target country be willing to change rather than suffer or start war.
So would these sanctions even be effective? Sanctions on gasoline are thought to be the most effective; however, there are some who think that the flow of gasoline into the country will not be decisively shut off as smugglers are prepared to supply the good at higher prices.
The US or Israel may becoming more prepared to attack Iran's nuclear development facilities. On Sunday, Iran prepared for this exact scenario. Perhaps they are asking for it.