Iran’s state TV is reporting that construction has begun on a second nuclear power reactor at its Bushehr plant amid heightened tensions over Tehran’s collapsing nuclear deal with world powers. Authorities began pouring concrete for the base of the reactor on Sunday in the presence of journalists in Bushehr, some 700 kilometers (440 miles) south from Iran’s capital, Tehran. Bushehr relies on 4.5% enriched uranium, which Iran is producing in violation of its 2015 nuclear deal.