As Donald Trump dismantles federal agencies, his administration is also creating a chill among non-governmental groups, cowing non-profits, intimidating universities and extracting commitments from law firms to support his aims. Officials have launched investigations into progressive and climate organizations, colleges and recipients of government grants. Experts worry that if nongovernmental groups are frightened into silence, US democracy may not weather the strain. “Trump has a strikingly authoritarian instinct,” said Steven Levitsky, a Harvard political science professor who co-authored the book How Democracies Die. “This is what authoritarians do, they go after civil society,” he added, referring to organizations that exist...