There's often been differences of why people think the US launched its attack on Iran.
Al Jazerra interview on currently, In which, Rubio clearly states and restated it was due to Iran's progress towards nuclear weapons. He stated that the US will never allow Iran to have nuclear weapons since the danger is too great.
He said there are outcomes that they would like such as regime change but the primary motive has always been to stop Iran from development of nuclear weapons.