U.S. Customs Commissioner Ray Kelly is adding agents and money to his agency’s strategic-investigations unit because of Chinese efforts to smuggle out advanced U.S. weapons components and know-how. Last month agents thwarted China’s second attempt to obtain military gyroscopes used in guidance systems for “smart” munitions, missiles and fighter aircraft. More customs cases are under way involving Chinese efforts to pilfer so-called critical technologies. FBI counterespionage specialists fear that the problem of spying isn’t confined to Chinese visitors to the national labs. The FBI is taking a hard look at activities by scientists from several other nations, most notably Iran. For some years, Iranian scientists have visited the labs for exchanges that are ostensibly peaceful and beneficial, such as counterproliferation talks. Still, security at the labs has been so lax that FBI officials now want to find out if the Iranians or other foreigners picked up arms-related information on the sly.