The Awami National Party, which recently broke off its alliance with the ruling party of Minister Nawaz Shariff, on Saturday declared open war on the Prime Minister over the controversial Kalabagh dam issue, accusing him of trying to impose the rule of Punjabis on the country.Protesting what it called Mr Sharif's plans to "impose the one unit system" on the country, the party said it would fight any proposed legislation of Mr Sharif's Pakistan Muslim League on the Kalabagh Dam.