British Prime Minister David Cameron has said new treaties on defense and nuclear co-operation with France marked a ï¿½new chapterï¿½ in a long history of defense co-operation. Speaking alongside French President Nicolas Sarkozy, Cameron said it would make both countries' citizens safer and would save money. A center will be set up in the UK to develop nuclear testing technology and another in France to carry it out. The leaders also confirmed plans for a joint army expeditionary force. The World's Laura Lynch reports from London.