WASHINGTON  - Severely strained ties between the United States and Pakistan are poised to improve after the two countries agreed on Tuesday to reopen ground routes key for the war in Afghanistan, Pakistan’s ambassador to the United States said.“We appreciate Secretary Clinton’s statement, and hope that bilateral ties can move to a better place from here. I am confident that both countries can agree on many critical issues, especially on bringing peace to the region,” Ambassador Sherry Rehman said in a statement.