The US said “nothing is agreed until everything is agreed” on lifting its sanctions on Iran, indicating that an immediate breakthrough to unlock some $7 billion of Iranian assets frozen in South Korea could be difficult.

State Department spokesman Ned Price made the remarks Tuesday in the US, when asked about whether the issue of Iranian funds frozen in South Korea due to US sanctions will be resolved soon. It comes as South Korean First Vice Foreign Minister Choi Jong-kun is in Vienna this week to meet with representatives from Iran and world powers taking part in talks to revive the tattered 2015 Iran nuclear deal, formally known as the Joint Comprehensive Plan of Action.

An eighth round of talks resumed Monday between Iran and Britain, China, Russia, France and Germany, along with the European Union, in Vienna to restore the JCPOA.

The US is participating indirectly in the talks as it unilaterally withdrew from the JCPOA in 2018.

Choi is set to meet separately with negotiators on the sidelines of the nuclear talks to discuss how to resolve the issue of frozen Iranian assets held in South Korea.

Noting that some “modest progress” was made in the ongoing talks, Price said sanctions relief, together with the nuclear steps that Iran needs to make for mutual compliance between Washington and Tehran with the JCPOA, is at the heart of the ongoing session in Vienna.

“Nothing is agreed until everything is agreed when it comes to these issues. So I wouldn’t want to get ahead of where we are,” he said when asked about the US position on the potential release of Iranian assets frozen in South Korea.

Tehran has been demanding Seoul release about $7 billion in revenue from oil sales, which has been tied up in Korean banks since 2019 due to sanctions reimposed on Iran by the Donald Trump administration, after Washington’s unilateral decision to withdraw from the 2015 nuclear accord. President Joe Biden is looking to rejoin the deal, but on condition that Tehran returns to full compliance.

Seoul has been consulting with Washington on ways to unlock the funds, but the US has yet to approve a release.

South Korea is not part of the JCPOA, but it has been discussing with signatory countries ways to resolve the frozen Iranian fund issues. A Foreign Ministry official clarified that Choi will not be part of the JCPOA talks, but his separate meetings with related countries could serve as an opportunity to resolve the Iranian asset issue before it’s too late.