The United States has said that it encourages the development of bilateral relations between Pakistan and China.
The US said it does not see anything new in the nuclear defence treaties that were signed during the recent visit of the Chinese President Hu Jintao to Islamabad.
"We encourage development of bilateral relations between Pakistan and its neighbors. China and Pakistan have a long history of relations. As for any, sort of, nuclear angle on this, I'm not aware of anything new that was announced or is allowed for by these agreements.
"So I don't think there's anything new on that front," State Department Spokesman Sean McCormack said.
Noting that China is a growing power, he said, "We would ask that China play a constructive role in the international community. It is developing economically, diplomatically, politically, militarily."
"China is going to be an important power on the international scene for some time to come. And we would hope that as it develops and as it defines its future role on the international stage that it plays a constructive role," he said.
During his visit to Pakistan, Chinese President Hu Jintao held talks with his Pakistani counterpart Pervez Musharraf and agreed to continue to enrich the contents of bilateral strategic and cooperative partnership by expanding practical and reciprocal cooperation in various fields.
Hu made a five-point proposal for the further growth of bilateral relations and the two sides signed a number of cooperative documents including an agreement on free trade.
Asked whether the US concerned about the military expansion of China, McCormack said, "The way it was put is we are concerned about their military buildup. We believe that it is outsized for their stated regional issues that they need to take on, or they need to address.
"The main issue that we have had is an issue of lack of transparency in that buildup," McCormack added.
"We have encouraged, over time, more military-to-military relations between the US and China so that we become more familiar with one another, so that we understand better how each other operates, what our objectives are, what are strategies are, what are tactics are, so there are no misunderstandings. And that is something that is slowly developing.
"There was recently a joint search-and-rescue mission exercise between US forces and Chinese forces. So that's a positive development. These are things that are going to take some time, again, as China starts to define itself differently on the world stage," McCormack said.