Iran on Thursday said it would continue to enrich uranium for research purposes but was ready to resume talks with the P5+1 group of world powers over its nuclear program, adding it was waiting for the European Union to set a time and place for the negotiations.

“We are waiting for Lady Ashton to call Dr. Jalili, and Dr. Jalili is obviously ready to take the call,” Iran’s deputy negotiator Ali Bagheri told Reuters, referring to the EU’s foreign policy chief Catherine Ashton and Saeed Jalili, Iran’s top negotiator.

Iran needed to enrich uranium to 20 percent for the research facility in Tehran and was converting part of its uranium stockpile to reactor fuel, Bagheri said, adding four more reactors were being built for research purposes.

Iran’s nuclear program is widely believed to be intended for military purposes, a claim Iran denies. Tehran has been conducting talks with the five permanent members of the UN Security Council plus Germany over curbing its enrichment activity for some two years, with few breakthroughs.

The US says it prefers to pursue diplomacy, but all options — including a military operation — are on the table and being considered to stop Tehran.

Last week Secretary of State John Kerry said he was disappointed by the last round of inconclusive talks in Kazakhstan earlier this month, but insisted that a diplomatic resolution is still the best option.

Those talks ended with the parties admitting that a wide gulf remained between the sides, and no concrete plans to meet again.

On Tuesday, former IDF Military Intelligence chief Amos Yadlin said that Iran had now crossed the “red line” set by Israel for its nuclear activity, and would be able to break out to the bomb by this summer.

Uranium enriched to 20% or higher is banned by international agreements, and viewed as a step toward manufacturing nuclear weapons.