Foreign firms attempting a takeover or merger that might affect national security must get a stamp of approval from a little-known group called the Committee on Foreign Investments in the United States, a panel of representatives from across the government run by the Treasury Department from its grand building on Pennsylvania Avenue, next to the White House.

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An interagency panel called the Committee on Foreign Investment in the United States, which looks at foreign investments for any national-security risk, has informally adopted what one official calls a "hard-look doctrine" toward any Russian attempts to invest in critical American industries.

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