President Joe Biden declined to impose a direct punishment for a massive cyberattack blamed on Chinese intelligence officials because U.S. allies aren’t prepared to join in such a confrontational step, according to a key U.S. official.

Biden’s team accused China’s Ministry of State Security last month of maintaining a network of “criminal contract hackers” responsible for a Microsoft Exchange attack that affected “tens of thousands of computers around the world.” That denunciation was echoed by allies around the world, including an unprecedented statement by NATO, but Biden stopped short of imposing the kinds of sanctions that characterized his response to analogous attacks by Russia.