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But the new sanctions also underscore the challenge the United States faces in isolating Iran, which has busily spun off hundreds of front companies, and renamed or reflagged dozens of ships, to get around existing sanctions.
"This is really a game of whack-a-mole," said Mark Dubowitz, the executive director of the Foundation for Defense of Democracies and an expert on Iranian sanctions. "These are incremental measures. What are needed now are measures more akin to economic warfare than these targeted, pinpoint measures."
Among the companies designated by the Treasury are Electronic Components Industries and Information Systems Iran, which are subsidiaries of an entity that is, in turn, controlled by the Iranian Ministry of Defense. The companies work on semiconductors, circuit boards and mainframe computers that have both civilian and military uses.
Also on the blacklist are four men — three Iranians and an Austrian — that the Treasury Department said support Iran's nuclear and missile programs. Under the sanctions, Americans are barred from doing business with these individuals, and any assets they have under American jurisdictions are frozen.
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