Joseph Biden will be the most experienced first-time president in nearly 30 years when he enters office, but he and his team will inherit a civil-military relationship as tenuous as any in recent memory. Not only will they have to deal with the fallout of President Donald Trump’s unusual legacy as commander-in-chief, they will need to try to avoid some of the unhealthy civil-military dynamics left over from the Obama administration. Biden and his team will grapple with all of this through a national security establishment that has changed in some important ways since Democrats last were at the helm. This would be a daunting assignment even in a stable time, but — given the potential threats on the horizon and the other crises Biden inherits — restoring a healthier civil-military balance will be especially challenging. Civilians may have the right to be wrong, but the margin for error in this environment is slim.