Mr. Gates said his discussions were marked by agreements and disagreements. The two sides announced new steps toward establishing a telephone hot line to avert misunderstandings between their militaries. This was viewed as significant by senior Pentagon officials, who said the Chinese government did not have such a line with any other nation.  Mr. Gates and his counterparts also announced an agreement to organize a new joint naval exercise, larger and more complex than previous exercises; a plan to exchange military students; and a promise to open Chinese archives to help account for American soldiers still listed as missing from the Korean War.  When asked to respond to American criticisms of the military and expansion, General Cao, the defense minister, replied, “It has been a normal deployment of our military force in our own territory.”  Mr. Gates acknowledged that he had made little headway in getting answers from the Chinese on their unannounced test of an antisatellite weapon in January, in which they destroyed an aging Chinese weather satellite. Western governments pressed for an explanation, but the Chinese government took nearly two weeks to publicly confirm the test and to say it had no plans for a space race. Worries over the circumstances and motive of the test remain.  “I raised our concerns about it, and there was no further discussion,” Mr. Gates said.  Mr. Gates also said he had raised with his Chinese hosts “the importance of increased pressures” to persuade Iran to drop any plans to develop nuclear weapons.  China has growing economic ties with Iran. During Monday’s meetings, Chinese officials expressed an understanding that the nation’s goal of steady energy supplies to power its economy could be threatened by nuclear proliferation in the Middle East, according to senior Pentagon officials traveling with Mr. Gates.  One senior official, speaking on standard diplomatic rules of anonymity to describe the private talks, said late Monday that Chinese officials had agreed that “a nuclear-armed Iran is something we are united in opposing.”  A version of this article appears in print on , on Page A9 of the New York edition with the headline: Gates Questions China on Military Growth. Order Reprints| Today's Paper|Subscribe
Defense Secretary Robert M. Gates’s visit was intended to nurture a complex relationship and press for more open communication over military issues.