The United States' top South Asia diplomat was to meet Pakistan President Asif Ali Zardari on Monday as the troubled country tackles growing Islamic militant insurgency and an economic crisis. Richard Boucher arrived in Pakistan after a series of US missile strikes into the country's tribal regions that have strained bilateral relations. Boucher and Zardari would "discuss the 'war on terror' and Pakistan's worsening economic problems," a Pakistani government official said on condition of anonymity. Pakistan has denied being at risk of defaulting on its foreign loans or suffering a balance of payments crisis.