Officials from the United States and Iran exchanged sharp criticisms over Tehran’s nuclear program at the opening of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) review conference, with the dispute expected to continue throughout the four-week meeting.

The disagreement centers on the election of Iran as one of 34 vice presidents of the conference. Iran had been nominated by the Non-Aligned Movement, a group of 121 mainly developing countries, The Caspian Post reports, citing Al Jazeera.

The US received backing from Australia and the United Arab Emirates, while the United Kingdom, France, and Germany also voiced “concern” over the appointment. Russia, however, objected to what it described as singling out Iran.

A US representative, whose name was not immediately available, stated that the Trump administration was “deeply shocked” that a country it accused of showing “contempt” for the treaty was appointed to a vice presidential role.

In response, Iran’s ambassador to the United Nations in Vienna, Reza Najafi, firmly rejected the US remarks, describing the accusations as “baseless and politically motivated.”