European diplomats will meet with Iran’s deputy foreign minister in Istanbul on Friday to try to restart negotiations on limiting or eliminating Iran’s nuclear enrichment program.

Britain, France and Germany have been urging Iran to talk again with the United States on its nuclear program and to make a concrete step toward restoring international trust in Iran’s insistence that its program is purely civilian in nature, despite enriching enough uranium to near weapons-grade to make 10 nuclear weapons.

Iran had halted fledgling talks with the United States after Israel launched a 12-day war last month that damaged Iran’s nuclear facilities and other infrastructure.

If Iran resists, the Europeans say that they will initiate a procedure to restore severe United Nations and multilateral sanctions on Iran that were suspended under a landmark 2015 nuclear deal because Iran has been violating its terms.

The agreement, in which Iran agreed to limit its nuclear program in exchange for sanctions relief, expires in mid-October. The Europeans are willing to extend the deadline on restoring the sanctions because once they are restored, they are useless as leverage.