MUNICH (AP) - Iran's foreign minister on Sunday welcomed the United States' willingness to hold direct talks with Tehran in the standoff over its nuclear program but didn't commit to accepting the offer - insisting that Washington must show "fair and real" intentions to resolve the issue and complaining about "threatening rhetoric." Ali Akbar Salehi insisted that no Iranian "red line" is getting in the way of direct negotiations with Washington, but also pointed to deep mistrust between the two countries. Salehi was speaking at the same international security conference where Vice President Joe Biden on Saturday said the United States was prepared talk directly to Iran. Biden insisted that Tehran must show it is serious and that Washington won't engage in such talks merely "for the exercise." Washington has indicated in the past that it's prepared to talk directly with Iran on the nuclear issue, but so far nothing has come of it. Meanwhile, talks involving all five permanent members of the U.N. Security Council plus Germany have made little headway, while several rounds of international sanctions have cut into Iran's oil sales and financial transactions. The next round of talks with the six powers will be held Feb. 25 in Kazakhstan, Salehi told the Munich Security Conference. Diplomats from some of those world powers have expressed frustration in recent weeks about what they say are Iran's tactics of proposing several venues but not committing to any single one for the talks. The EU had proposed dates and venues since December, "so it is good to hear that the Foreign Minister finally confirmed now," said Michael Mann, a spokesman for EU foreign policy chief Catherine Ashton. We hope the negotiating team will also confirm. Salehi said Biden's comments marked "a step forward," but indicated getting the U.S. and Iran together for one-to-one talks will be no easy task. "We have no red line for bilateral negotiations when it comes to negotiating over a particular subject," Salehi said. If the subject is the nuclear file, yes, we are ready for negotiations but we have to make sure ... that the other side this time comes with authentic intention, with a fair and real intention to resolve the issue. Salehi said it was "contradictory" if the U.S. voices willingness to hold direct talks "but on the other side you use this threatening rhetoric that everything is on the table ... these are not compatible with each other." "We are ready for engagement only when it is on equal footing," he said. Iran insists it does not want nuclear arms and argues it has a right to enrich uranium for a civilian nuclear power program, but suspicion persists that the real aim is to build an atomic bomb. Last month Iran, in a defiant move, announced plans to vastly increase its pace of uranium enrichment. Vali Nasr, dean of the Paul H. Nitze School of Advanced International Studies at Johns Hopkins University, sounded a skeptical note about direct Iran-U.S. talks any time soon. "I think these are good statements that both sides are at least open to this, (but) I think there have to be some ideas about how you get them to the table in a credible way," he said. One of the worst things is that if they went to the table and then they fail ... then we really will be at an impasse. "So I think that's very key, that when that moment comes there's actually some forward momentum built into the talks," Nasr said. Salehi underlined Iran's role as "an important regional player" and told the conference: "We are the golden key to the region." Iran is a key ally of embattled Syrian President Bashar Assad. On the sidelines of the Munich meeting, the minister met the top Syrian opposition leader, Moaz al-Khatib. Salehi welcomed al-Khatib's statements over the past week that he would be willing to sit down with representatives of Assad's regime as "a good step forward." But amid international calls for Assad to go, he insisted that "we do not need prescriptions from outside." "Iran has talked to the opposition, we are not categorizing the opposition, we are ready to talk to all opposition," Salehi said. "We are ready to be part of the solution," he insisted. The sooner that we resolve the issue, the better it is. Associated Press writer Don Melvin contributed to this report from Brussels.