Officials from the United States and Iran have sparred over Tehran’s nuclear ambitions at the opening of the nuclear non-proliferation treaty review, Al Jazeera reports.

At issue is Iran’s election as one of 34 vice presidents of the conference. Iran was a candidate from the Non-Aligned Movement, comprising 121 mainly developing countries.

The US was backed by Australia and the United Arab Emirates, and the United Kingdom, France and Germany have also expressed “concern.” Russia has objected to singling out Iran.

The US representative, whose name was not immediately available, says the Trump administration is “deeply shocked” that a country that’s demonstrated “contempt” for the treaty is now a vice president.

Reza Najafi, Iran’s ambassador to the UN in Vienna, categorically rejected the US statement, calling the allegations “baseless and politically motivated”.