The article states that exports of windmill blades and accessories from Tamil Nadu to the U.S. are facing a “twin blow”. The first blow is the additional 25% tariff that became effective on Wednesday, which is on top of existing duties. The second is a national security investigation launched by the U.S. Commerce Department into the import of wind turbines and their components. These two factors are likely to affect the shipping of blades from the state, which is a major hub for wind energy manufacturing.