Experts in law enforcement say the violent protests in Charlottesville, Va., last weekend offer cities around the country a chance to learn how to better prepare for rallies in the future in which white nationalists are likely to be met by counter-protesters.

Virginia’s public safety officials have broadly defended the police response in Charlottesville, but have also admitted some shortcomings. Virginia State Police spokeswoman Corrine Geller said both groups were granted permits to rally, and said police set up a barrier between the two groups.