The U.S. State Department this week said terror attacks and rising anti-American sentiment in Pakistan meant U.S. citizens should be wary of traveling to the country.
"Protests have taken place across Pakistan against the United States, International Security Assistance Force and NATO," the warning read.
The warning followed claims that a missile fired allegedly by a U.S. military drone aircraft killed a top commander in the militant Haqqani network in Pakistani territory.
State Department spokeswoman Victoria Nuland said the warning wasn't indicative of any particular change in diplomatic relations or a heightened terrorism thereat.
"We do this on a routine basis as events happen on the ground," she said.
Nuland said the Pakistani alert had nothing to do with the upcoming anniversary of the al-Qaida attacks in the United States on Sept. 11, 2001.
A book written by a member of the Navy SEAL team that killed al-Qaida ringleader Osama bin Laden is due on shelves next week. Ties between the Washington and Islamabad deteriorated following the 2011 raid that killed bin Laden at his compound in Pakistan.