Three European powers met with an Iranian minister to try to reopen negotiations over the limits of its nuclear activities.

U.S. President Donald Trump expressed frustration with Iran’s leadership on Sunday, telling reporters on the sidelines of a meeting with the European Commission that Tehran doesn’t seem to comprehend the scale of the damage done to its nuclear program.

European and Iranian diplomats have arrived in Istanbul in a renewed effort to resolve the standoff over Tehran's nuclear program. The talks mark the first formal engagement since June's 12-day war between Iran and Israel, a conflict that included U.S. airstrikes on Iranian nuclear facilities and heightened tensions across the region.