A Richfield police officer who was seen on video striking a Somali-American teenager in the fall of 2015 must be reinstated to the force, an independent arbitrator said Wednesday, and police officials in the first-ring suburb aren't happy about that.

Officer Nate Kinsey had been fired by the city of Richfield. Instead, the arbitrator said, he will serve a three-day suspension and again be a member of the department.

"We are extremely disappointed with the arbitrator's decision," Richfield Police Chief Jay Henthorne said in a news release Wednesday. "We do not agree with this decision nor do we condone this type of behavior.

"The Richfield Police Department is trying to create a culture of personal responsibility and build community trust at a time where police officers are not necessarily looked at favorably," he wrote. "[Kinsey] was given every opportunity to correct his behavior as it relates to his duties. ... He simply did not change his behavior as it relates to using and documenting use of force, so the city had no other alternative except to terminate his employment."

The news release said the city "will be considering the use of body cameras for its officers, extensive retraining of all sworn police personnel, and is also currently weighing appeal options."

The union representing Kinsey released a statement Wednesday evening saying, "We are pleased with the arbitrator's decision to reinstate officer Kinsey.

"[He] is held in high regard by his fellow officers and supervisors and is known for his honesty, commitment, and dedication," said Sean Gormley, executive director of Law Enforcement Labor Services. "The incident in question demonstrates the challenges officers face on a regular basis. [It] also illustrates the pitfalls of jumping to conclusions based on partial video and audio recordings.

"Officer Kinsey recognizes the arbitrator's decision as a chance to demonstrate a renewed commitment to serving the community of Richfield with dignity and respect for others," the statement concluded.

The incident, which happened about 11:15 a.m. on Oct. 3, 2015, was recorded on cellphone video. Kinsey was seen pushing and striking Kamal Gelle, then 19, after a traffic stop near Adams Hill Park at 72nd Street and Washburn Avenue S.

Kinsey and another officer who was involved in the incident were placed on leave by the city. Kinsey had been disciplined before by Richfield police for improper use of force, including a warning for hitting suspects in the head.

The Hennepin County attorney's office and a special prosecutor working for the city of Richfield announced on Dec. 31, 2015, that no criminal charges would be filed against Kinsey in connection with the Gelle incident.

Police union contracts allow officers to grieve discipline or termination and take it to an arbitrator. That can be a long process; in Kinsey's case, the decision came almost 15 months after the incident.

Richfield police Lt. Mike Flaherty called the arbitrator's decision "frustrating."

"I thought we did a really good job of putting the case together," Flaherty said Wednesday night. "We dotted our i's and crossed our t's but the arbitrator saw it differently.

"It's a little disappointing when you have the outcry for police accountability and these guys get their jobs back," he said.

Kinsey, 41, also was accused in a federal lawsuit of punching a man while the man sat in the back seat of a car that had been stopped by Richfield police in December 2011. In January 2013, he was reprimanded by the department after he repeatedly hit an intoxicated man in the face with his elbow and fist.