The Army is converting two of its brigade combat teams to add more armor.

The change comes as the Pentagon looks to prepare for a potential fight with an evenly matched adversary.

The Pentagon is also trying to boost its armored presence in Europe, where NATO seeks to deter Russia.

The Pentagon is making a military-wide shift to prepare for a bigger, more intense fight against a peer or near-peer competitor, and the latest part of that shift means big changes to the mission and makeup of two Army units.

The Army announced on Thursday that the 1st Brigade Combat Team of 1st Armored Division, based at Fort Bliss in Texas, will change from Stryker Brigade Combat Team equipped with Stryker armored vehicles to an Armored Brigade Combat Team outfitted with tanks in spring 2019.

The service also said that the 2nd Brigade Combat Team of the 4th Armored Division, based at Fort Carson in Colorado, will change from an infantry brigade to a Stryker brigade in spring 2020, adding about 500 personnel and hundreds of the eight-wheeled armored vehicles.

A Stryker Infantry Carrier Vehicle with a new 30 mm chain-gun, in Stara Boleslav, Czechia, May 30, 2018. US Army/Sgt. Timothy Hamlin

Army officials characterized the changes as part of the effort to increase the service's lethality and effectiveness.

"The Army leadership determined that we needed to convert two brigade combat teams to armor and Stryker in order to deter our near-peer adversaries or defeat them if required," said Maj. Gen. Brian J. Mennes, director of force management.

"Converting a brigade combat team from infantry to armor insures the Army remains the world's most lethal ground combat force, able to deploy, fight and win against any adversary, anytime, and anywhere," Army Secretary Mark Esper said.

A M1A1-SA Abrams from D Troop, 6th Squadron, 8th Cavalry Regiment, 2nd Armored Brigade Combat Team, 3rd Infantry Division, moves to battle position during troop-gunnery qualification at Fort Stewart, Georgia, March 29, 2018. US Army/Staff Sgt. Nathan C. Berry

The Army has made other conversions in order put more armor on the battlefield.

In October 2017, the 2nd Brigade Combat Team of the 3rd Infantry Division, based at Fort Stewart in Georgia, completed its conversion from an infantry brigade combat team to an armored brigade combat team, adding 18 Paladin self-propelled howitzers, 138 Bradley fighting vehicles, and 87 Abrams tanks.

'Units aren’t built just overnight'

A major goal for the Army is to boost its armored presence in Europe as part of a NATO effort increase the alliance's deterrence posture in the face of what many see as a growing Russian threat in the region.

Other changes underway include adding better defense systems and more firepower to tanks and armored vehicles.

A US soldier guides an M1 Abrams tank from 1st Armored Brigade Combat Team, 1st Cavalry Division, off ARC vessel Endurance at the Port of Antwerp, Belgium, May 20, 2018. US Army/Sgt. 1st Class Jacob A. McDonald

Army units rotating through Europe have also put more emphasis on maneuvering around the continent, a facet of combat operations that was deemphasized after the Cold War and is now complicated by a tangle of administrative and bureaucratic restrictions on movements across national borders.

The Army is also working to rebuild the readiness of its brigade combat teams, after nearly two decades of combat operations, buildups, and drawdowns.

The service's goal is to have 66% of the active-duty Army's brigade combat teams and 33% of the Army Reserve's and Army National Guard's teams at the highest level of readiness over the next three years, Army Chief of Staff Gen. Mark Milley said in March.

Converting the Fort Bliss- and Fort Carson-based units will bring the regular Army and National Guard to a total of 58 brigade combat teams.

"Units aren’t built just overnight, and their readiness isn’t built overnight, as you know," Milley said at the time.