The United States and India are expected to sign an agreement today that would take a major step toward allowing the sale of sophisticated US arms to the South Asian nation. The pact could prove a boon to US companies, including Lockheed Martin and Boeing. Both firms are in the running to compete for India’s plan to buy 126 multi-role fighters, which would be one of the largest arms deals in the world. The announcement is expected to be made as Secretary of State Hillary Clinton visits India. Clinton is also expected to sign an agreement enabling US companies to sell nuclear reactors to India, a deal that will likely benefit General Electric and Westinghouse Electric. Meanwhile, on Sunday India rejected calls by the US to accept mandatory national cuts in carbon dioxide emissions.