Russia and Iran are set to sign agreements this week to build new nuclear power units in Iran, according to Iran’s nuclear chief, Mohammad Eslami.

Eslami, also Iran’s vice president, made the announcement during a visit to Moscow.

Western governments accuse Iran of violating the 2015 nuclear deal aimed at preventing a weapons program, while Iran denies any such intention.

Russia supports Iran’s right to develop nuclear energy for peaceful purposes.

Meanwhile, Russian President Vladimir Putin offered U.S. President Donald Trump a one-year extension of the New START treaty on nuclear arms control.

The treaty limits deployed strategic nuclear warheads to 1,550 for both countries, the Jerusalem Post has reported.

Without an extension, both Russia and the U.S. could exceed these limits, heightening global nuclear tensions.