U.S. Defense Secretary Leon E. Panetta on Monday welcomed Chinese Defense Minister Gen. Liang Guanglie to the Pentagon for a broad discussion of security issues that include North Korea, Afghanistan and counter-piracy. A key issue the U.S. will explore is the objective of China's "very robust and rapid" military modernization, especially in a region that is "at peace," a senior defense official told reporters. The talks are aimed at building military-to-military cooperation in several areas, including humanitarian assistance, disaster relief, space, and cyberspace, the official said. "This visit is occurring at an important time as we're seeking to expand cooperation, improve mutual understanding, build greater mutual trust, and reduce our differences," the official said. Gen. Liang's arrival marks the first visit to the U.S. by a Chinese defense minister in nine years. He will spend the week touring military installations, including the U.S. Military Academy at West Point, N.Y.; Fort Benning, Ga.; and Camp Lejeune, S.C. Gen. Liang toured a naval base in San Diego on Saturday.