Nerval's Lobster writes: T-Platforms, which manufactured the fastest supercomputer in Russia (and twenty-sixth fastest in the world), has been placed on the IT equivalent of the no-fly list. In March, the U.S. Department of Commerce’s Bureau of Industry and Security added T-Platforms’ businesses in Germany, Russia and Taiwan to the “Entity List,” which includes those believed to be acting contrary to the national security or foreign policy interests of the United States. U.S. IT companies are essentially banned from doing business with T-Platforms, especially with regards to HPC hardware such as microprocessors, which could be used for what the government views as illegal purposes. The rule, discovered by HPCWire, was published in March. According to the rule, Commerce’s End-User Review Committee (ERC) believes that T-Platforms may be assisting the Russian government and military conduct nuclear research—which, given historical tensions between the two companies, apparently falls outside the bounds of permitted use. An email address that T-Platforms listed for its German office bounced, and Slashdot was unable to reach executives at its Russian headquarters for comment.