The International Atomic Energy Agency's (IAEA's) director general Yukiya Amano told an IAEA board meeting on 10 June that he was concerned about rising tensions over Iran's nuclear programme and called for de-escalation through dialogue.

Tensions rose after the USA increased economic sanctions against Iran following its withdrawal from the 2015 Joint Comprehensive Plan of Action (JCPOA) in May 2018, and demanded that all countries and companies stop imports of Iranian oil or face financial sanctions themselves. Under the JCPOA – signed with the USA, UK, France, Russia, China and Germany – Iran had agreed to limit its nuclear development programme in return for the lifting of sanctions. The other JCPOA signatories continue to support the deal.  During a joint news conference with US President Donald Trump on 4 June, UK Prime Minister Theresa May stressed the importance of the USA-UK special relationship in dealing with Iran, but added that "we stand by the nuclear deal".

On the first anniversary of the US withdrawal from the nuclear deal, Iran announced that it would suspend implementing some of its commitments under the deal, and that it would stop exporting excess uranium and heavy water, setting a 60-day deadline for the remaining parties to the deal to take practical measures to safeguard its interests in the face of the American sanctions.

In its quarterly report on 31 May, the IAEA said Iran's increased stocks of key nuclear materials are still within the limits set by the nuclear deal. However, Amano confirmed that Iran has accelerated its production of enriched uranium. According to the report, the IAEA verified that production of heavy water at the Heavy Water Production Plant (HWPP) had stopped between 15 April  and 22 May 2019, but had now resumed, and that Iran’s stock of heavy water was 125.2t, an increase of 0.4t on February but still under the 130t limit. As of 20 May, Iran had 174.1kg of enriched uranium, up from 163.8kg in February but again within the relevant limit.