Obama: Iran sanctions can still be avoided, but are the next step for U.N.

President Barack Obama on Tuesday left the door open for the Iranian regime to avoid new U.N. sanctions, but said the measures were the "next step" to counter its nuclear ambitions.

The president's words come as international pressure has ramped up on Iran after it announced it would enrich uranium to 20 percent purity, bringing it closer to weapons-grade.

The Iranian regime has not agreed to a deal proposed by several countries to allow other nations to enrich its uranium for medical research, which it says is the intent of its nuclear program.

"[Their refusal to negotiate] indicates to us that despite their posturing that their nuclear power is only for civilian use, that they in fact continue to pursue a course that leads to weaponization and that is unacceptable to the international community," Obama said during a surprise appearance at the daily White House press briefing.

"The next step is sanctions. they have made their choice so far but the door is still open," he added.

Obama's words could be the final chance for Iran to avoid a fresh round of sanctions. Defense Secretary Robert Gibbs said said this week that he wants the punishment deal out "within weeks" and not months.

The president had set a deadline for the end of 2009 for Iran to come to the negotiating table, but the regime under President Mahmoud Ahmadinejad has still not obliged.

Obama commended Russia, which recently indicated it could back the sanctions for being "forward leaning on this issue."

But the U.S. is still finding it hard to reach unanimity on the sanctions. China, which is a top trade partner with Iran, still has not backed the sanctions and would still like to pursue a deal on nuclear fuel production.

Efforts to get China on board with the sanctions have been complicated by a series of trade disputes between the U.S. and the Asian country.

Obama said that "we'll have to see" how China responds to the new call for sanctions but he expressed confidence that " right now that the international community is unified around Iran's misbehavior in this area."

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