A few of Pennsylvania’s representatives in Washington are asking federal officials to block the sale of U.S. Steel. Senators Bob Casey and John Fetterman, along with Congressman Chris Deluzio, sent a letter to Treasury Secretary Janet Yellen yesterday, claiming, allowing Japanese firm, Nippon Steel, to acquire the company would compromise national security. Yellen is the chair of the Committee on Foreign Investment, a body that evaluates the impact of investments from other nations in the U.S. The letter goes on to point out that Nippon Steel has operations in China, a country that is considered a U.S. adversary.