The U.S. State Department last week said terror attacks and rising anti-American sentiment in Pakistan meant U.S. citizens should be wary of traveling to the country.
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.
Haqqani commander Mali Khan was arrested in Afghanistan last year on charges of managing insurgent bases in the country and in neighboring Pakistan. The Haqqani network attacked the U.S. Embassy in Kabul in October but wasn't listed as a terrorist organization at the time.
"I have sent a report to Congress saying that the Haqqani network meets the statutory criteria of the Immigration and Nationality Act for designation as a Foreign Terrorist Organization," said U.S. Secretary of State Hillary Clinton in a statement Friday.
The Pakistani intelligence agency allegedly has ties to the Haqqani network. A report in Pakistani newspaper the Express Tribune last month cited a "senior American military official" as saying Washington felt the Haqqani network could play a key role in a future Afghanistan.
U.S. Army Brig. Gen. Stephen Twitty, a spokesman for U.S. Forces-Afghanistan, had said the claims were "categorically false."