Dubai, United Arab Emirates — Iran has begun construction at its Natanz nuclear facility, newly-released satellite images show. The images were made public as the U.N. nuclear agency acknowledged Tehran is building an underground advanced centrifuge assembly plant after its last one exploded in a reported sabotage attack last summer.

The election’s outcome likely will determine which approach America takes. Heightened tensions between Iran and the U.S. nearly ignited a war at the start of the year.