Iran raised the extent of its defiance of the world when it began enriching uranium to a level approaching 20 percent. In the West, there is wide agreement that this step is bringing Iran closer to having a nuclear bomb. And as with every instance in which Iran takes such a step, or when information is revealed regarding the military nature of its nuclear program, the world is easily shocked and the call goes out for more decisive action. In practice, however, these are just hollow words.

U.S. President Barack Obama took office against the backdrop of intensified disclosure of military nuclear activities in Iran. At the end of September, when the enrichment facility that was built near the Iranian city of Qom was disclosed, Obama enlisted support from French President Nicolas Sarkozy and British Prime Minister Gordon Brown. He expressed his insistence that the situation was serious, and that if Iran did not alter its path there would be consequences. But there weren't.

And in October, when the deal to enrich uranium outside Iran was presented, Tehran was initially given a two-week extension and was then given until the end of the year. American Secretary of State Hillary Clinton warned that the United States would not wait forever. In the meantime, however, the U.S. is waiting.

The end of the year, the deadline that Obama set for evaluating diplomatic progress on Iran, also came and went. It is hard to avoid the conclusion that nothing has been accomplished, and it has been clear that the essential next step will involve imposing sanctions. In January, however, with China in the rotating presidency of the United Nations Security Council, it was said that it was necessary to wait until February, when France would assume the post.

February has arrived, but the Chinese are still opposed to sanctions and the Iranians are enriching their uranium to a higher level. Obama's response is that he has had it and the time has come for sanctions and immediately - which means within a few weeks, perhaps by the end of March. In March, however, Gabon will assume the presidency of the Security Council, and it is not certain that Iran is at the top of its agenda. And there are still the problems with the Chinese.

And if we assume that ultimately there will be sanctions, so what? The involvement with sanctions, who's for and who's against, when, why and to what extent, deflects from the primary problem - the absence of an American strategy for tough negotiations with Iran. Even more serious, however, is that there are worrying signs that the Obama administration is beginning to resign itself not only to the fact that Iran will continue to enrich uranium, but also to recognition that the Islamic republic could ultimately build a nuclear bomb.

When you begin to reconcile with a specific reality, you stop trying to change it. And then we hear more about the need to deter and contain Iran than about stopping it, about a nuclear umbrella for America's allies in the Persian Gulf instead of a firm negotiating strategy against Iran. And sanctions alone won't stop Iran.

The role of sanctions and other pressure, such as credible military threats, is to convince Iran that time is not on its side and it would be better to seriously negotiate with the West. Only then will the diplomatic work of American-Iranian negotiations begin, with a goal of an arrangement that would eliminate the Iranian nuclear threat.

There is no sign that the Obama administration intends to mobilize the necessary political muscle to lead such a process. An additional decision on ineffective sanctions will apparently satisfy the U.S. So, we tried.

The weakness that Obama is showing toward Iran has implications for America's global leadership role. Israel must speak to the Americans about this, and instead of focusing on sanctions, should try to determine if and how the U.S. intends to lead a comprehensive process leading to a solution. Without genuine American determination, there is no prospect of preventing the Iranians from developing nuclear weapons.

The writer is a senior research associate at the Institute for National Security Studies, where she is also director of the Arms Control and Regional Security Project.