Washington and other veto-holding permanent members in the UN Security Council are studying sanction options if Iran does not prove its nuclear program is for peaceful purposes, US ambassador to the United Nations Susan Rice said Sunday. Speaking on NBC television's "Meet the Press," she said that the so-called P-5 + 1 is in a period of "intense negotiations" with Teheran but that Iran had a "finite period" to completely open its nuclear program to international inspections. She refused to set a deadline. Rice said the United States had three options: to push sanctions through the UN, to work with European allies to punish Iran, or to take unilateral action in conjunction with the other possible courses of action. Nonetheless, US President Barack Obama's national security adviser, James Jones, said that Washington was pleased by some positive signs of cooperation from Iran about its nuclear program. "For now, things are moving in the right direction," he said, speaking after hearing from the head of the UN nuclear watchdog agency that international inspectors would visit Teheran's newly revealed uranium enrichment site on Oct. 25. "Iran came to the table and seemingly showed some degree of cooperation and that's a good thing. The world is sending a strong message to Iran and North Korea, and we're seeing some positive reaction," Jones said. The national security advisor also denied a New York Times report that due to new intelligence regarding Iran's nuclear program, the US would be reassessing its 2007 National Intelligence Estimate [NIE] which posited that Iran halted its nuclear weapons program in 2003. "We stand by the reports that we put out. You're going to get a lot of speculation," Jones told CNN. Regarding recent talks between the international community and Iran over Tehran's nuclear program, Jones said the last couple of weeks have been "significant", as the Iranians have announced they will open their recently revealed nuclear facility near Qom for inspection. Jones said that the next round of nuclear talks would focus on finding a methodology of how Iran will transfer uranium to Russia for enrichment.