The United States and Vietnam are preparing to stage joint naval exercises in a show of unity that has been closely watched by China. US warships have docked at Vietnamese ports in recent days highlighting rapidly warming relations between the former enemies. Beijing has stepped up claims to disputed islands in the south China sea that are also claimed by Vietnam and other neighbours. Beijing has always protested against the involvement of any other parties in the south China sea dispute saying it was a matter for bilateral negotiations. This latest development show a remarkable warming of the relationship between the two former enemies.