The Chicago Police Department on Thursday canceled days off and put officers on 12-hour shifts to bolster the force by up to 4,000 officers –– enough to handle any adverse reaction to a verdict in the trial of Jason Van Dyke for the murder of Laquan McDonald.

“Either way it goes, there’s gonna be people unhappy on either side of this,” Police Supt. Eddie Johnson told the Sun-Times as the jury started its deliberations.

“But this is our city that we call home. And there are ways to voice your concerns in a peaceful manner. And that’s what I expect from the citizens of this city.”

Starting at 7:30 a.m. Thursday and continuing until further notice, police officers normally dispersed between three watches were instead assigned to one of two, 12-hour-tours: 7 a.m.-to-7 p.m. and 7 p.m.-to-7 a.m.

Specialized units have staggered starting times throughout the day, “depending on operational developments,” officials said.

It’s all part of a 116-page operational plan that “accounts for nearly any possible circumstance” and has been in the works for months, officials said.

“This is the thing about protests: The best-laid plans never go the way that you plan it to go. So, we have no focus area at this point. That focus will come into play once we determine where, if we do have protests,” Johnson said.

The plan was put in place Thursday, hours before closing arguments concluded and jury deliberations began in a murder trial that has captivated Chicago and the nation.

“The most powerful tools in the plan are basically administrative components for the department to be able to call in large groups of officers with almost no notice. We’re already in that deployment action,” said Police Department spokesman Anthony Guglielmi.

“Because you’re on 12-hour tours, an entire shift of officers for the entire city are now available for discretionary deployment. And that’s a lot of officers — somewhere in the neighborhood of 3,000-to-4,000.”

Based on a dialogue between community leaders and police that started after the court-ordered release of the McDonald shooting video, the police department anticipates demonstrations, but “no plan for organized violence and organized destruction,” Guglielmi said.

But he acknowledged that hate-filled fliers posted around the city and chatter on social media has police paying particular attention to the Northwest and Southwest Side neighborhoods that are home to scores of Chicago police officers.

That includes Beverly, Morgan Park and Mount Greenwood, where local Ald. Matt O’Shea (19th) told constituents that “special attention will be added for critical infrastructures, including schools, churches and retail areas.”

In 2016, a 25-year-old Indianapolis man who was in Chicago to attend a funeral was shot and killed by two off-duty police officers after a racially-charged brawl in the predominantly white Mount Greenwood neighborhood.

“We have teams of officers in Area Central. We have a team of officers at City Hall. We have teams of officers on Michigan Ave. The reason why we’ve put officers in Mount Greenwood is there’s been some disrespectful communication that we’ve come across on social media channels. You may have seen the fliers where people are saying ‘Let’s demonstrate in the neighborhoods where officers live,'” Guglielmi said.

“In Mount Greenwood, we certainly have had issues there before with demonstrators. They came to heightened [tensions] at the point. But for the most part, they were managed peacefully.”

Unlike the 2012 NATO Summit, Chicago police officers will not be dressed in riot gear. They will simply be in uniform wearing bullet-proof vests and helmets and carrying Tasers.

“Let’s say you see cops standing out on every corner in riot gear with rifles. What does that say to people? That we’re ready for a fight. And that’s not simply the fact,” Johnson said.

Complicating the logistical planning is Sunday’s Chicago Marathon and Monday’s Columbus Day Parade and the massive police involved in the search for a spree killer in Rogers Park.

Johnson is hoping to handle all of it without going to the next level: Calling in the Illinois State Police and police departments from the suburbs and other states.

“That’s always a possibility if we have to. We can always request help from the Illinois Law Enforcement Alert System. We can always do that,” Johnson said.

The Chicago Public Schools also braced for the verdict.

South Loop Principal Tara Shelton sent a letter to parents, warning that, if the jury reaches a verdict during school hours on Thursday or Friday, “We will immediately go into lock down drill protocol for both buildings. All exterior doors will remain closed and recess will move indoors.”

Shelton also promised further details about a “plan for dismissal and extended day.”