W itnesses from key federal agencies could not give an answer why the United States hasn’t sanctioned China for its cyberattacks against Microsoft and other U.S. companies, responding to Sen. Ted Cruz’s question on Tuesday with silence. Earlier this month, the Biden administration and a host of U.S. allies blamed China ’s Ministry of State Security for a massive hack against the Microsoft Exchange Server. But the U.S. did not impose sanctions like it did against Russian intelligence hackers earlier this year over the SolarWinds attack, and it did not charge anyone related to the Microsoft hack. “Let me ask…