West Florissant Avenue in Ferguson, Missouri, looked more like downtown Kiev or Tahrir Square for much of last week. Protesters reacting to the alleged excessive use of force by a police officer who killed an unarmed African-American teenager, were greeted by police wielding a 30-ton mine-proof truck, machine guns, sniper rifles and an array of other military hardware.

The military posture is the result of the federal government funneling vast amounts of military hardware to local police since the terrorist attacks of Sept. 11, 2001, on the theory that local police are on the front lines against terrorism.

In St. Louis County alone, the federal government has spent more than $9.4 million on military equipment, including the mine-proof truck and two helicopters.

But terrorism remains rare, and it should not be confused with people's exercise of their constitutional right to protest. Those who engage in violence against people or property remain subject to arrest and prosecution, as always.

The formidable hardware is a weapon of intimidation against American civilians. Its presence in Ferguson clearly contributed to the tension, which was relieved only when the state police intervened and opted for communication rather than intimidation.

Whether local police departments need armored personnel carriers and high-power weaponry typically used by the military is questionable. But if they must have it, it should come with very strict rules for its limited use.