The Russian hackers that masterminded the SolarWinds hack—which breached the networks of multiple U.S. government agencies last year in one of the most sophisticated attacks ever detected—are back. In a blog post, Tom Burt, Microsoft’s vice president of customer security, warned that the Russian-based Nobelium group has launched a fresh campaign targeting government agencies that deal with foreign policy. Burt wrote that the hackers managed to gain access to an email marketing service at the U.S. Agency for International Development, and have also targeted “many humanitarian and human-rights organizations.” Burt went on: “These attacks appear to be a continuation of multiple efforts by Nobelium to target government agencies involved in foreign policy as part of intelligence-gathering efforts.” He said the new wave of attacks hit 3,000 email accounts at more than 150 different organizations, but didn’t say how many of those hacking attempts were successful.