U.S. Secretary of State Marco Rubio has vowed that the United States will respond forcefully if Venezuela attacks Guyana amid an ongoing territorial dispute that includes massive oil and gas reserves.

United States Secretary of State Marco Rubio issued a stern warning to Venezuela on Thursday, stating that any aggression toward Guyana or U.S. oil major

U.S. Secretary of State warned Venezuela on Thursday that it would be "a very bad day" for the South American country if it were to attack its neighbor Guyana or U.S.-based energy giant ExxonMobil, in comments that threatened unspecified action in such a case.