US ambassador Anne W. Peterson on Thursday called on the chief of his own faction of the Pakistan Muslim League Mian Nawaz Sharif here and discussed the relief activities for the internally displaced persons (IDPs) affected by ongoing military operation in Malakand Division, report said. According to sources, the US ambassador discussed the matters of bilateral relations and exchanged views over the affects of military operation in tribal areas. On the occasion, she expressed resolve of US government to fight the menace of militancy terming it a common threat to both the countries. The PML-N leader urged the US to play an effective role for the rehabilitation of Swat IDPs facing sever hardships in refugee camps after their displacement.