Iranian Foreign Minister Mohammad Javad Zarif on Wednesday expressed optimism about the nuclear talks with world powers which are set to reconvene on Thursday, saying the negotiations were moving forward thanks to “seriousness and strong political will.”

Iran and the P5+1 nations — the US, UK, France, Germany, China and Russia — were set to meet in Geneva in order to put the interim nuclear deal reached in November into action.

“We believe that progress and entering the next difficult stage … is completely possible through the other side’s commitment to the Geneva agreement,” Zarif wrote on Facebook, according to a Fars News translation.

Ahead of the talks, a senior Iranian negotiator warned the US not to impose additional sanctions on the Islamic Republic, saying previous sanctions “soured the atmosphere” of negotiations with world powers, Fars News reported.

“These moves will certainly not be helpful and we have announced in our meetings with the American side that such attempts will sour the atmosphere (of the talks),” Deputy Foreign Minister Takht Ravanchi was quoted by the semi-official news agency saying.

The diplomat was quoted by another official news agency saying that the deal signed in November with world powers has transformed the West’s approach to Iran from confrontation to interaction.

The two-day talks coming up in Geneva will focus on the remaining issues concerning implementing the deal “pending a political decision” by Tehran ahead of the date it’s set to take effect on January 20, an Iranian Foreign Minister spokesperson said.

At the turn of the New Year Iran and Western negotiators reported they were nearing an understanding on the details of implementing the landmark agreement with Tehran. Zarif said the technical talks which took place in December yielded “positive results.”

The nuclear accord puts strong limits on Iran’s uranium enrichment program in return for an easing of some international sanctions on Tehran for six months while a permanent deal is negotiated. The United States and its allies believe Iran’s nuclear program is aimed at producing a nuclear weapon, a claim that Tehran denies, saying it is intended only for peaceful purposes.

A US State Department official said last month that there has been progress in the talks and the teams have taken “a few outstanding points” back to their governments for consultation. “The two sides expect to finalize the implementation plan soon,” the official said in late December.

Under the accord, Iran is to limit enrichment to producing uranium enriched at 5 percent, the level needed to power a reactor to produce electricity. Uranium enriched to around 90 percent is needed to produce a nuclear warhead. Iran would also neutralize its stockpile of 20-percent-enriched uranium, a level used to power research reactors.