Mohammad Javad Zarif, the foreign minister of Iran, warned that an upcoming trip to Vienna by U.S. Ambassador to the United Nations Nikki Haley to discuss Tehran’s nuclear activities with international atomic watchdog officials goes against the spirit of the landmark nuclear accord.

In a letter addressed to senior officials at the European Union and the International Atomic Energy Agency, a UN watchdog group, Zarif said Haley’s intent “to press” the IAEA on Iran’s compliance “flies in the face” of the deal that sharply limited Tehran’s ability to produce nuclear material in exchange for the lifting of most U.S. sanctions.

Zarif said the Trump administration designed the trip to sew doubt among the accord’s signatories and private companies regarding the pact’s stability and future sustainability in an attempt to undermine the agreement.