WASHINGTON (Reuters) -U.S. Special Envoy for Iran Rob Malley plans to travel to Vienna over the weekend for fresh talks on reviving Iran’s 2015 nuclear deal with major powers, U.S. State Department spokesperson Ned Price said on Wednesday.

The talks seek to find a way for the United States and Iran to resume compliance with the agreement, under which Iran restricted its nuclear program in return for relief from U.S., European Union and U.N. sanctions.

Then-President Donald Trump pulled the United States out of the deal in 2018 and reimposed U.S. sanctions, prompting Iran to start violating the nuclear restrictions about a year later. Iran struck the original deal with six major powers: Britain, China, France, Germany, Russia and the United States.

Enrique Mora, the senior European Union official chairing the talks, said on Twitter (NYSE:) that they would resume on Thursday.

The talks have effectively been indirect negotiations between Iran and the United States, with diplomats from other nations shuttling between them because Tehran has refused face-to-face meetings with U.S. officials.

Noting the EU statement that talks resume on Thursday, the State Department spokesman told reporters: “We understand that there will be a day of meetings before the heads of delegations need to attend … so Special Envoy Malley and his inter-agency delegation will plan to join the talks over the weekend.”