Officials from the U.S., Russia and other major world powers in charge of assessing the implementation of the Iran nuclear deal met in Vienna on Friday with delegates from Iran amid growing questions about the U.S. commitment to the plan.

Iranian Deputy Foreign Minister Abbas Aragchi and other delegates refused to comment on the closed-door session after it wrapped up and before bilateral meetings were expected to begin.

The periodic meeting of the so-called Joint Comprehensive Plan of Action Joint Commission, or JCPOA, was being closely watched for an indication of American thinking following President Donald Trump’s firing of U.S. Secretary of State Rex Tillerson this week.

Trump has vowed to walk away from the 2015 agreement in mid-May unless European countries join the U.S. in addressing what the president says are its key flaws. These include no penalties for Iran’s missile work and support for militant groups in Lebanon, Syria, Yemen and elsewhere.

Tillerson’s firing and the choice of anti-Iran hard-liner Mike Pompeo to replace him have fueled speculation that Washington will pull out — a move that seems likely would kill the deal.

Aragchi told a parliamentary committee in Tehran on Wednesday that Tillerson’s ouster was proof that Trump would pull out and promised that Iran would withdraw if the U.S. does.

In addition to the U.S., Russia and Iran, the Vienna meeting included delegates from the European Union and China.

State Department policy planning chief Brian Hook, who led the U.S. delegation, has scheduled a press briefing later in the day.

The nuclear deal, which was negotiated during the Obama administration, limits Iran’s enrichment and stockpiling of material that could be applied to a nuclear weapons program. In exchange, Tehran was granted widespread relief from international trade, oil and banking sanctions.

Trump’s next deadline to extend some of those concessions is May 12, and he has vowed not to do so again unless the Europeans meet his demands.

EU foreign ministers, who will meet to discuss the issue Monday in Brussels, are expected to affirm that they believe the deal with Iran is good, and work to discourage Trump from pulling out of the deal in May. At the same time, they’re expected to start putting greater stress on Iran’s missile development and its destabilizing role in the region.

(AP)