Obama says Iran sanctions offer no guarantees

US President Barack Obama said in an interview aired on Friday that there is no guarantee sanctions will change Iran's behavior but he believes steady international pressure could alter Tehran's nuclear calculations over time.

"If the question is, do we have a guarantee as to the sanctions we are able to institute at this stage are automatically going to change Iranian behavior, of course we don't," Obama told ABC's "Good Morning America."

"The history of the Iranian regime, like the North Korean regime is that you know, you apply international pressure on these countries, sometimes they choose to change behavior, sometimes they don't."

Obama spoke to ABC on Thursday after signing a landmark nuclear treaty with Russia that provided the US administration with a much-needed diplomatic achievement and a step toward better ties with Moscow.

Obama and Russian President Dmitry Medvedev also pledged greater cooperation to persuade Iran to give up its uranium enrichment program, which the United States views as a covert effort to develop nuclear weapons. Iran denies the accusation and says its nuclear activity is an energy program aimed at generating electric power.

"I think it's an enormous shift and a signal that Russia, like the United States, recognizes that unless we can get all countries to start abiding by certain rules of the road, and right now, our biggest concerns are obviously Iran and North Korea," the US president said.

"If we are consistent and steady in applying international pressure ... over time, Iran, which is not a stupid regime, which is very attentive and watching what's happening in the international community, will start making a different set of cost-benefit analyses about whether or not pursuing nuclear weapons makes sense for them," he said.