The United Sates on Monday welcomed the announcement by Presidents Hamid Karzai of Afghanistan and Asif Zardari of Pakistan of the implementation of a bilateral Transit Trade Agreement. "This step is a concrete demonstration of the common shared vision of the development, prosperity, and peace the two presidents share, and it will make a significant contribution to regional stability," State Department deputy spokesman Mark Toner told reporters. "The full implementation of the treaty will provide an economic boost for both countries by reducing the costs and delays involved in transport from Afghanistan to world markets and across Afghanistan to markets in Central Asia and beyond," Toner said. "The United States remains committed to assisting Afghanistan and Pakistan as well as their neighbors in expanding regional trade ties," Toner added.