It's the ONLY question. .mil bases, post roads, and DC. That's all that's listed in the Constitution.
Keep on supporting the FedGov though. "Go Team! Burn those 'squatters' out!"
If one supports private property rights as it is one of the primary support legs of a free enterprise capitalist economy, then the rights of the state must match and be equal to the rights of the citizens. IOW, the government can exercise the same control and restrictions over government land as the private citizen is able to exert on their land.
If however, one does not support property rights, then the non-owner can claim squatter's rights to exercise control over other people's property. When you open that door, the relationship changes between the citizen and the state and then opens the door for socialism / Marxism as the state then becomes the final arbitrator over who's rights are supreme.