Fourteen pieces of American art purchased by Iran nearly four decades ago, but blocked for export from the United States because of the 1979 Iranian revolution and rupture in relations, have finally been delivered, both nations said Friday.

Delivery of the art, described by American officials as architectural drawings bought in 1978 by the Tehran Museum of Contemporary Art, came against the backdrop of a slightly improved atmosphere in the estranged ties between Iran and the United States since the agreement resolving Iran’s disputed nuclear work was reached in July.