The United States has reacted cautiously to a deal between Pakistan and Taliban in the restive Swat valley, saying that while there is a track record of such agreements not working, it will be supportive if it meets the benchmark of ending domestic and international terrorism.

Washington is willing to see what results the deal brings in and would be supportive if it end terrorist violence, brings in individuals outside the political process into political process and supports continued development of Pakistan and its institutions, State Department's deputy spokesman Tom Casey told reporters.

"The standard isn't whether they've talked with tribal militants or whether they have talked with individuals or groups or not," he said. The bottom line, Casey stressed, is whether the agreement actually responds to the concerns of the United States and Pakistan for ending domestic and international terrorism and stops cross border violence between tribal areas in Pakistan and Afghanistan.

But the official said that there had been similar kinds of agreements in the past, which have not worked. "That means that there's track record that is not particularly positive," Casey said.

Under the agreement, Pakistani troops would gradually withdraw from Swat Valley in return for assurances that militant cleric Fazlullah's supporters would stop attacks and some social reforms including allowing girls to go to school would be implemented.

The agreement was singed this week by Pakistan's new government, despite opposition from the US, which feels that it would give the terrorists breathing space and allow them to carry out attacks in Pakistan and abroad.