The United States is declaring the Pakistan-based Haqqani network a terrorist organization, a move that paves the way for tough financial sanctions against the militant group.

Secretary of State Hillary Clinton announced Friday that she had signed a report to Congress that says the network meets the criteria for a terrorist designation. The Obama administration will also urge other countries to freeze any Haqqani assets.

The Haqqani network has been blamed for a series of high-profile attacks on U.S. and NATO forces in Afghanistan, including an attack at the U.S. Embassy in Kabul last year.

The group, which has ties to the Taliban and al-Qaida, operates from Pakistan's North Waziristan tribal area. It is also believed to have close ties with key elements of Pakistani intelligence — a charge Pakistani officials have rejected.

Senior Haqqani commanders said the terror designation shows the U.S. is not sincere about peace efforts in Afghanistan. They told Reuters news agency the move would result in “hardship” for U.S. soldier Bowe Bergdahl, held captive since disappearing in 2009 from his base in Paktika province.

The Pentagon declined Friday to discuss details of efforts to gain the soldier's return. But a spokesman (George Little) welcomed the announcement, saying U.S. forces will continue with “aggressive military action against this threat” to U.S. security in the region.

The Pakistani embassy in Washington called the U.S. move to blacklist the Haqqani network a U.S. “internal matter.” It said Pakistan would continue to work with all international partners, including the United States, in combating terrorism.

However, Afghanistan analyst Lisa Curtis of the U.S.-based Heritage Foundation voiced skepticism about Pakistani efforts to pursue the network.

“Well, I am sort of doubtful that Pakistan is going to change any of its policies overnight. Let's take for example [the banned militant group] Lashkar-e-Taiba. They have been listed as a foreign terrorist organization by the U.S. for the last 10 years, yet Pakistan has not really taken any concrete measures to shut that group down. So I think that, you know, it would be premature to expect Pakistan to take any concrete measures on its own.”

Congress has been pressing to have the entire network branded a terrorist organization because it is now widely seen as the biggest threat to U.S. and allied forces in Afghanistan. Clinton faced a September 9 U.S. Congressional deadline for making a decision concerning the entire group.

However, some U.S. officials have expressed concern that placing the network on a blacklist could further damage already fragile relations with Pakistan and slow efforts to negotiate a political settlement to the Afghan war by undercutting talks with the Taliban.

Months of sour relations between the U.S. and Pakistan are only just now easing with July's reopening of crucial military supply lines across the Afghan border. Pakistan had closed the routes after 24 Pakistani troops were killed in a U.S. air strike last year.

The U.S. has been pressing Pakistan to launch a military offensive in North Waziristan, but the Pakistani army has said its forces are stretched too thin to target militants in the tribal agency.

Afghan Interior Ministry spokesman Sediq Sediqqi on Friday welcomed any move by the United States to target the Haqqani network.