"Ten years after the JCPOA came into force, the UNSC re-imposed sanctions on Iran. We engaged in very intensive diplomatic efforts with Iran ahead of, and during the 30-day window after the snapback was triggered by France, Germany and the United Kingdom," Kaja Kallas, Vice-President of the European Commission said in her opening speech at High Level Forum on Regional Security and Cooperation.

"This however did not result in creating the conditions for a possible extension of the relevant UNSC Resolution. The European Union will now re-impose all previously lifted UN and EU nuclear-related sanctions without delay," Kallas said.

"But the snapback of sanctions and nuclear restrictions must not be the end of diplomacy. In this spirit, I will continue to reach out to all stakeholders, including Iran," she noted.

Because a sustainable solution to the Iranian nuclear issue can only be achieved through negotiation and diplomacy, Kallas underscored, adding, "Together we can work to make Iran a responsible partner in the region."