The National Institutes of Health (nih.gov), the National Library of Medicine (nlm.nih.gov), the clinical center (cc.nih.gov) and the National Cancer Institute (cancer.gov) ** have all been taken offline. Trying to connect generates a “server not...
Technical discussions on other sites have suggested it was likely a simple goof on a firewall setting update since DNS had continued responding over TCP throughout the outage but not UDP. In any case it's all fixed now which would not be the case if it had been deliberate. Occam's Razor still applies.
There has been a lot of personnel churn so it could have been a lot of things ranging the spectrum of run of the mill goofs by staff, goofs by people coming into new roles ranging all the way up to insider activity by staff or vandalism by fired staff (very common). Or it could be a failed attack by adversaries NIH has always been a high priority target for state sponsored cyberattacks.
One thing it is certainly does not seem to be is deliberate action by the Administration otherwise it would have gone fully down and would have stayed down.