Bradley Cooper bulks up in 'American Sniper' trailer

Los Angeles: The first trailer for Clint Eastwood's new film 'American Sniper' has premiered.

Bradley Cooper leads the cast of the war drama, which tells the story of former Navy SEAL chief Chris Kyle, who has the greatest number of sniper kills in US military history, reports suggest.

Cooper is said to have gained 40 pounds for the movie, which is based on Kyle's autobiography.

Sienna Miller plays Kyle's wife Taya Renae, who is left to manage their family's home life while her husband is abroad. 'Homeland' star Navid Negahban and 'Boardwalk Empire's Eric Ladin are also in the supporting cast.

'American Sniper' will be released in cinemas on January 16, 2015.