“What Trump seems to be advocating here would be a fundamental violation of international law embodied in numerous international agreements and in recognized principles of customary international law,” said Anthony Clark Arend, a Georgetown University professor of government and foreign service.

Specifically, Arend cited the Annex to the Hague Convention of 1907 on the Laws and Customs of War, which says that “private property ... must be respected (and) cannot be confiscated.” It also says that “pillage is formally forbidden.”

In addition, Arend said, the 1949 Geneva Convention Relative to the Protection of Civilian Persons in Times of War provides that “any destruction by the Occupying Power of real or personal property belonging individually or collectively to private persons, or to the State, or to other public authorities, or to social or cooperative organizations, is prohibited, except where such destruction is rendered absolutely necessary by military operations.”

Richard D. Rosen, the director of Texas Tech University’s Center for Military Law & Policy, added that Trump’s idea “appears to constitute aggression of the type condemned by the United Nations by resolution in 1974.” The resolution states that “any military occupation, however temporary, resulting from such invasion or attack, or any annexation by the use of force of the territory of another State or part thereof” qualifies as an “act of aggression.”

Arend said the only way he could envision an idea like Trump’s being acceptable under international law would stem from sanctions imposed by the U.N. Security Council. But that would be moot in this case since the 2003 Iraq War was not undertaken with the approval of the Security Council.