President Barack Obama on Thursday unveiled a new defence strategy that will shrink the country's armed forces at a time of tight budgets but pledged to maintained U.S. military superiority in the world.

Our military will be leaner but the world must know - the United States is going to maintain our military superiority with armed forces that are agile, flexible and ready for the full range of contingencies and threats, Obama told a news briefing at the Pentagon.

(Reporting By Matt Spetalnick and Alister Bull)