Nomination of Exxon Mobil chief for State Department heralds more aggressive economic policies

US president-elect Donald Trump has chosen Exxon Mobil CEO Rex Tillerson to be his secretary of state, a move that observers said Trump sees as a way to secure smarter deals in economic diplomacy, particularly in trade agreements.

The choice is a crucial one - Trump has made statements provoking China - as the incoming president clearly intends to steer United States foreign policy in a more conservative direction.