China stepped up its allegations of U.S. cyberattacks Tuesday, with local law enforcement saying they were investigating three National Security Agency operatives they had placed on a wanted list and a national official condemning the alleged attacks.

State media outlet Xinhau advanced the claims in two stories, one detailing a hacking campaign during the Asian Winter Games alleged by the Harbin Public Security Bureau and another pinned to a briefing from Chinese foreign ministry spokesperson Lin Jian.

“China condemns the above-mentioned malicious cyber activity by the U.S. government,” Lin said. “We urge the U.S. to take a responsible attitude on the cybersecurity issue, and stop any attack, including cyberattack, and groundless vilification against China.”

China has in recent years begun pointing the finger back at the United States, which has accused Beijing of backing a litany of cyberattack, but Tuesday’s allegations were more specific and aggressive than usual. Relations have soured further between China and the United States under the Trump administration as both nations escalate tariffs.

The Wall Street Journal reported this week that China had privately acknowledged Beijing was behind a series of cyberattacks on U.S. infrastructure. The remarks were “indirect and somewhat ambiguous, but most of the American delegation in the room interpreted it as a tacit admission and a warning to the U.S. about Taiwan, a former U.S. official familiar with the meeting” told the newspaper.

As detailed in the Xinhau account, police in Harbin, the capital of the Heilongjiang Province, the NSA’s alleged focus was the Asian Winter Games.

“Investigations revealed that the NSA focused its pre-event cyberattacks on critical systems of the Asian Winter Games, including registration, arrival/departure management, and competition entry platforms, authorities said,” the story reads. “These systems, essential for pre-event operations, stored vast amounts of sensitive personal data of individuals associated with the Games.”

Chinese technical teams reportedly conducted investigations that concluded the NSA’s Tailored Access Operations Office carried out the attacks using front organizations to purchase IP addresses and rent servers anonymously. The goal, apparently, was to undermine normal operations of the Asian Winter Games.

The NSA also allegedly launched cyberattacks on critical infrastructure sectors in the Heilongjiang Province and had “transmitted unknown encrypted data packets” to devices running Microsoft Windows in an attempt to “activate or trigger pre-implanted backdoors.” And the NSA operatives also had launched attacks against companies such as Huawei, the Xinhau account states.

According to the story, technical teams implicated the University of California and Virginia Tech in the attacks as well.

The NSA, Virginia Tech and the University of California did not immediately respond to a request for comment.