In the last week, federal forces have seized, searched, questioned and even detained people on the streets of Portland, Ore. American citizens have seen agents from unidentified organizations, wearing military-style uniforms and markings suggesting they are “police” — but with no names or insignia identifying their agencies — use unmarked vehicles to abscond with detainees. Ken Cuccinelli, acting deputy secretary of the Department of Homeland Security (DHS), said Friday, “we intend to continue [these actions] not just in Portland but in any of the facilities that we’re responsible for around the country.”

Many citizens, Portland elected officials and more than a few legal authorities are questioning whether these forces are acting lawfully. Cuccinelli says they are protecting federal property; the governor of Oregon, the mayor of Portland and the Oregon attorney general say they are violating Oregonians’ civil rights and, according to a statement by the Oregon Department of Justice, which is suing, “overstepping their powers and injuring or threatening peaceful protesters on the streets of Downtown Portland.”

One thing is clear to me: They are neither civilian security forces nor military personnel as we know them in our society. These camouflaged and heavily armed agents execute some provisions of martial law while conducting law enforcement without the request or approval of local elected officials — operating in a risky and ill-defined no man’s land between traditional police roles and those of soldiers activated for specific missions associated with the suspension of legal norms. Straddling that boundary has the potential for serious and even dangerous repercussions.

In the United States, the police maintain law and order in society, and the military defends the Constitution against all enemies, foreign and domestic. There is a critical distinction between police officers and soldiers. While always inherently understanding that distinction, I found occasion to learn its explicit characteristics while on a deployment to Iraq.

During the “surge” of 2007-2008, I commanded a large multinational task force of U.S., allied and Iraqi soldiers in the north. The war had significantly depleted the Iraqi police force. While most of the newly graduated Iraqi police officers were being sent to Baghdad, we concluded one way to improve security in the seven northern provinces that constituted our area of operations was to expedite the training of police dedicated to our region. We asked our higher headquarters and the Iraqi government for support to dramatically increase the number of police officers serving the 11 million Iraqi citizens living in this large area.

The task, as we saw it, was threefold: help recruit Iraqis who would be trained to serve as police officers; build large facilities at remote sites to conduct that training, and provide U.S. soldiers who would help train the recruits in law enforcement and public safety skills. Iraq needed these additional police forces to help reduce crime and civic unrest, and our task force needed more partners in providing security for the communities where we were fighting.

While I had served in various Army training organizations, I didn’t know much about the intricacies of police training. Luckily, our task force was blessed with a savvy military police lieutenant colonel, who served as our divisional MP battalion commander. In early conversations, this MP professional helped me understand that our task in expanding the force would be very different from the one we had in training soldiers, and he highlighted three cultural differences between police and soldiers.

First, while soldiers and police both “bear arms,” a police officer’s main goal wielding a weapon is to keep the peace, control the population and apprehend criminals. Professional militaries, on the other hand, vow to defend nations; they use weapons to threaten, intimidate and kill adversaries. Great police forces, the MP commander emphasized, are trained in ways to be less threatening, so they can protect and serve their communities while also apprehending criminals. While some police units certainly have Special Weapons and Tactics units, or SWAT teams, those units require extensive training and are reserved for dire circumstances. Use them too often or incorrectly, and you lose the trust of the citizens that the police are asked to protect and serve.

Second, there is the matter of uniforms. We were rapidly expanding our recruiting and training of future Iraqi police officers so we could put thousands in the cities quickly, but the interior minister — the Baghdad official charged with growing the nascent police force — couldn’t get us the large number of uniforms we needed for those we were graduating. The minister asked if we would accept camouflage outfits instead of police uniforms for the graduates, and he asked if we would also accept unmarked pickup trucks for service as police cruisers.

“Tell him, ‘Hell, no,’” the MP commander told me emphatically. When I asked why, he explained the history of the blue police uniform, as well as the psychological role that a uniform plays in law enforcement. The traditional “blues” started with the London “bobbies” of the early 1800s, whose uniforms were designed to distinguish the British police force from the British military. Our nation’s first organized police, in New York, continued this tradition in the 1850s, numerous other American cities followed suit, and now most nations associate the police officer with blue uniforms.

Myriad studies have shown interesting results: For example, some research shows citizens adjust behaviors when someone wearing a police uniform is nearby; others show that police uniforms are most likely to “induce feelings of safety” when compared to other uniforms or civilian clothes, and those wearing a blue uniform receive a high rate of cooperation when asked to perform a task. Wearing camouflage uniforms, our division MP commander said, would send the wrong message, especially in a society where neither the U.S. nor the Iraqi military was yet trusted by the population.

We wanted these new police officers to be on the street, visible, ready to be called. We came to realize that no matter what we needed to make it happen, we had to ensure our new graduates wore the distinctive uniforms, name tags and badges with numbers that were associated with the IP, the Iraqi Police. And the vehicles we got them needed to be painted and clearly marked, and different from anything they saw U.S. forces using. Camo should be saved for when you’re trying to blend in or hide, not when you’re patrolling the streets on foot or in cars.

We managed to get the police uniforms and marked vehicles.

The third difference involves accountability. As we began to develop the training package for the police officers — a program that consisted of the expected marksmanship training, arrest procedures, treatment of criminals and the like — the MP commander told me he needed additional time for accountability training. Police officers aren’t like soldiers, he explained. Soldiers work as part of a team, accountable to that team and a chain of command, laws of land warfare and a military justice system. Police work in pairs, sometimes alone, and rogue police officers often cover for one another. If a police officer doesn’t understand their accountability to the law they are sworn to uphold and the citizens they swear to protect and defend, they have the potential to turn into something worse than criminals. We included a course on professional accountability training, and at graduation the rookie officers repeated an oath written for them, to uphold the law.

Security forces — police and military — belong to unique and different professions, each critically important, each with a distinct culture. Like all professionals, they profess to certain standards, live by certain values and contribute in a special way to the society they serve. But they have similar goals: to gain the trust and confidence, not the “hearts and minds,” of the people they serve.

Specific training, uniforms and accountability to standards — for deadly actions on foreign battlefields or keeping the peace on the streets of our nation — are geared to radically different missions, and they are not interchangeable in any functioning democratic society.