U.S. Accuses China's Military in Cyberattacks WASHINGTON - The Obama administration on Monday explicitly accused China's military of mounting attacks on American government computer systems and defense contractors, saying one motive could be to map "military capabilities that could be exploited during a crisis." While some recent estimates have more than 90 percent of cyberespionage in the United States originating in China, the accusations relayed in the Pentagon's annual report to Congress on Chinese military capabilities were remarkable in their directness. Until now the administration avoided directly accusing both the Chinese government and the People's Liberation Army of using cyberweapons against the United States in a deliberate, government-developed strategy to steal intellectual property and gain strategic advantage. "In 2012, numerous computer systems around the world, including those owned by the U.S. government, continued to be targeted for intrusions, some of which appear to be attributable directly to the Chinese government and military," the nearly 100-page report said. The report, released Monday, described China's primary goal as stealing industrial technology, but said many intrusions also seemed aimed at obtaining insights into American policy makers" thinking. It warned that the same information-gathering could easily be used for "building a picture of U.S. network defense networks, logistics, and related military capabilities that could be exploited during a crisis." It was unclear why the administration chose the Pentagon report to make assertions that it has long declined to make at the White House. A White House official declined to say at what level the report was cleared. A senior defense official said "this was a thoroughly coordinated report," but did not elaborate. Missing from the Pentagon report was any acknowledgment of the similar abilities being developed in the United States, where billions of dollars are spent each year on cyberdefense and constructing increasingly sophisticated cyberweapons. Recently the director of the National Security Agency, Gen. Keith Alexander, who is also commander of the military's fast-growing Cyber Command, told Congress that he was creating more than a dozen offensive cyberunits, designed to mount attacks, when necessary, at foreign computer networks. When the United States mounted its cyberattacks on Iran's nuclear facilities early in President Obama's first term, Mr. Obama expressed concern to aides that China and other states might use the American operations to justify their own intrusions. But the Pentagon report describes something far more sophisticated: A China that has now leapt into the first ranks of offensive cybertechnologies. It is investing in electronic warfare capabilities in an effort to blind American satellites and other space assets, and hopes to use electronic and traditional weapons systems to gradually push the United States military presence into the mid-Pacific nearly 2,000 miles from China's coast. The report argues that China's first aircraft carrier, the Liaoning, commissioned last September, is the first of several carriers the country plans to deploy over the next 15 years. It said the carrier would not reach "operational effectiveness" for three or four years, but is already set to operate in the East and South China Seas, the site of China's territorial disputes with several neighbors, including Japan, Indonesia, the Philippines and Vietnam. The report notes a new carrier base under construction in Yuchi. The report also detailed China's progress in developing its stealth aircraft, first tested in January 2011. Three months ago the Obama administration would not officially confirm reports in The New York Times, based in large part on a detailed study by the computer security firm Mandiant, that identified P.L.A. Unit 61398 near Shanghai as the likely source of many of the biggest thefts of data from American companies and some government institutions. Until Monday, the strongest critique of China came from Thomas E. Donilon, the president's national security adviser, who said in a speech at the Asia Society in March that American companies were increasingly concerned about "cyberintrusions emanating from China on an unprecedented scale," and that "the international community cannot tolerate such activity from any country." He stopped short of blaming the Chinese government for the espionage. Correction: May 7, 2013 An earlier version of this article gave the incorrect number for the unit identified by a New York Times article in February as the likely source of many of the biggest thefts of data from American companies and some government institutions. It is P.L.A. Unit 61398, not 21398. The name of China's first aircraft carrier was also misspelled. It is the Liaoning, not the Lianoning.