US Secretary of State Hillary Clinton today arrived in Pakistan on a surprise visit amid severe strains in bilateral ties following the American raid that killed al-Qaeda Chief Osama bin Laden earlier this month. Ms. Clinton and US Joint Chiefs of Staff Chairman Admiral Mike Mullen, who arrived in Islamabad on Thursday night, will hold talks with Pakistan's civilian and military leaders. Ms. Clinton is expected to pressure the Pakistan government to take more steps to flush out terrorists from the country. An official said, Clinton will tell Pakistan to act against senior al-Qaeda targets, and also against factories producing explosives for use against US troops in Afghanistan and to support Taliban reconciliation.