In Lithuania, the Museum of Genocide Victims holds stark reminders of the Nazi and Soviet Union occupations that devastated the Baltic state.

To see the facilities used by the KGB and, prior to them, the Nazis, to hold prisoners and those who opposed the regime was "insightful," said Col. John DiGiambattista, whose soldiers from 1st Brigade, 1st Cavalry Division, just completed a rotation of Operation Atlantic Resolve in Europe.

"For those folks, the threat from Russia is real," he said. "Their freedom is a unique thing, and they certainly don't take it for granted. It's very real for them."

Just months after bringing home the last of its M1 Abrams tanks and Bradley Fighting Vehicles from Europe, the Army's heavy vehicles are back in the region as it faces a new but familiar threat.

In the last 10 months, Russia has annexed the Crimea region, secured a vital port in the Black Sea and sponsored a civil war in Eastern Ukraine that has claimed thousands of lives — all within a few hundred miles of NATO's borders.

Russia's military also has taken on an aggressive swagger. In the Black Sea, NATO ships like the U.S. destroyer Donald Cook have been buzzed by Russian fighters. Russian Tu-95 Bear Bombers have reportedly been tracked near Canada conducting missile strike drills within range of targets in the United States, and Russian airplanes have been tracked as close as 50 miles from the California coast — the closest they've come since the end of the Cold War.

"My concern about those kinds of activities is there can be a miscalculation or mistake that could lead to a confrontation," said Lt. Gen. John Nicholson, commander of NATO Land Command. "When you look at the history of warfare, it's replete with examples where a miscalculation or mistake can spin into war."

The tensions amid this Russian aggression has pushed a region that took a backseat to the conflicts in Iraq and Afghanistan and saw a drawdown of 10,000 soldiers, including two heavy brigade combat teams, back into the spotlight.

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The Army is dialing up its missions in the regions with plans to:

Continue three-month troop deployments of about 800 soldiers, with the likely addition of aviation rotations. Contribute soldiers to a NATO response force of an expected 4,000 to 5,000 troops. Add a brigade's worth of tanks and Bradleys by the end of 2015.

All of these efforts by the U.S. Army in Europe is part of what Lt. Gen. Frederick "Ben" Hodges, commanding general of U.S. Army Europe, has dubbed "Strong Europe."

"Strong Europe is meant to convey the framework of what U.S. Army Europe, as a forward-stationed force, is able to provide on behalf of the Army to [European Command] and NATO," he said. "It's about relationships, the training centers, the infrastructure, as well as the organizations that are here."

Support for the region doesn't start and stop with the Army.

Senior military leaders, including NATO's top military officer, Air Force Gen. Philip Breedlove, are calling for a halt to the U.S. withdrawal from Europe. U.S. lawmakers are calling for the Defense Department to stop retiring F-15 aircraft in Europe and stop the removal of dual-capable aircraft from the European area of operations. The Navy has sent ships on presence missions to the Baltic and Black Seas.

Attack on one, attack on all

NATO in December certified Land Command, based in Izmir, Turkey, as the headquarters for a major joint operation, if needed, to command a large-scale, multi-corps employment of ground forces.

The Army has rotated troops — with their tanks and Bradleys — to train with the militaries in Poland and the Baltic states for the last nine months. These rotations, part of a series of exercises under Operation Atlantic Resolve, will continue into the New Year with soldiers from the 2nd Cavalry Regiment, followed by troops from 1st Brigade Combat Team, 3rd Infantry Division.

The Russians "illegally annexed Crimea," and they are now working to "fracture" the NATO alliance by "using all aspects of national power to create friction," Hodges said.

"I am sure that their No. 1 objective is to fracture the alliance, to put a wedge between the U.S. and Europe, and then, if they can, separate the different parts of Europe from each other," he said. "If countries don't believe fellow members would respond in an Article 5 situation, then they've really created a serious crack in the alliance and what it stands for."

Article 5 in the North Atlantic Treaty states that an attack on one member is an attack on all, and is "the core of what NATO is all about," Hodges said.

The task in front of NATO — and the U.S. — now is to assure its allies closest to Russia, Hodges said.

NATO Land Command was certified as a land component command during Trident Lance '14. During the exercise, the command led three NATO corps in a scenario where the alliance restored the territorial integrity of Estonia after it had been invaded. The exercise took place across nine locations with 3,700 troops, and it simulated two corps, or about 140,000 troops, attacking abreast through air assaults, large-scale ground maneuvers and special operations.

This capability — a return to large-scale ground operations after 13 years of counter-insurgency-focused operations in Iraq and Afghanistan — sends a message to friends and potential adversaries alike, Nicholson said.

"To our friends, it's reassuring to know that the alliance can conduct large-scale operations of this nature to protect one of its member states," he said. "No soldier wants war, but the best way to prevent conflict is to be prepared for it. In that sense, this preparation contributes to deterrence because … it should give anyone out there reason to stop and think before they threaten a member of the alliance."

Another priority for Land Command in 2015 is the Very High Readiness Joint Task Force, or VJTF.

This new quick-reaction force came out of the September NATO summit in Wales. It likely will have 4,000 to 5,000 troops, but its specific makeup remains unclear as leaders and planners work out the details in the coming months.

The VJTF is to reach initial operational capability in the fall of 2015 and full operational capability in early 2016.

"We're very deep into that [planning] right now in terms of what it looks like," Nicholson said. "The big challenge is rapid deployment and how we conduct that."

Soldier rotations

The Army, for its part, continues to send troops to Operation Atlantic Resolve, including an element from a division headquarters; commit troops to the NATO Response Force; and deploy soldiers to participate in multi-national exercises across the region such as the recent Combined Resolve III in Germany.

Hodges said he's "very excited" about the upcoming deployment of an element from 4th Infantry Division headquarters.

"They will come over probably with a deputy commanding general and staff, and spend several months here providing command and control over the rotational forces," he said.

At Fort Carson, Colorado, the 4th Infantry Division headquarters has been focused on Europe for months, said Maj. Gen. Paul LaCamera, the commanding general. He expects the division to be aligned with European Command for at least two years.

"We're working with the different forces over there and focusing on training and exercises, and how we can continue to build partner capacity and build on friendships and relationships we started, really, on the battlefields of Afghanistan," he said. "For the division itself, some of the NATO partners we're working with, they were part of our task force in [Afghanistan] last year. It's kind of exciting."

An element from the division likely will take over Atlantic Resolve operations in February, LaCamera said. The division also is preparing for a warfighter exercise in March.

A U.S. Soldier of 1st Battalion, 4th Infantry Regiment prepares to fire a rocket-propelled grenade during exercise Combined Resolve III at the Joint Multinational Readiness Center in Hohenfels, Germany, Nov. 6, 2014. Combined Resolve III is a multinational exercise, which includes more than 4,000 participants from NATO and partner nations, and is designed to provide a complex training scenario that focuses on multinational unified land operations and reinforces the U.S. commitment to NATO and Europe. (U.S. Army photo by Spc. Brian Chaney/ Released)

A soldier with 1st Battalion, 4th Infantry Regiment prepares to fire a rocket-propelled grenade during exercise Combined Resolve III at the Joint Multinational Readiness Center in Hohenfels, Germany on Nov. 6.

Photo Credit: Spc. Brian Chaney/Army

Part of the soldiers' training includes learning about Europe, its history and the current events unfolding in the region from local and military experts, LaCamera said.

One of the first stateside units to be deployed to Europe as part of its regional alignment was 1st BCT, 1st Cavalry Division.

Being on the ground and participating in Operation Atlantic Resolve gave his soldiers unique insight into the threat posed by Russian aggression, DiGiambattista said.

Spc. Ahmed Amin, an infantryman in 1st BCT's B Company, 2nd Battalion, 8th Cavalry Regiment, spend the last three months in Estonia.

"It was eye-opening, especially for those of us who had never deployed or left the U.S. before," he said.

Amin and his fellow soldiers got the chance to train with the Estonian army and gain some insight into their fighting style. The soldiers, who spent most of their time at the Estonian army base in Tapa, also got to give the Estonians a crash course in how the Bradley Fighting Vehicle works, Amin said.

The soldiers also were visited by Estonia's prime minister and president, he said.

"That was extremely humbling for us," he said.

Sgt. 1st Class Marc Manilla, also from B Company, and his soldiers spent most of their time at one of the Lithuanian army's main posts in Rukla.

"We trained pretty much the entire time we were there," said Manilla, a platoon sergeant who's deployed once to Iraq and once to Afghanistan.

Working with the Lithuanians "was an awesome experience," he said.

"I've been to several different countries, and they have a lot of pride, and they constantly train, and they always were seeking to be better, just like we were," he said. "It was good to go there, and they were open to learning how we do stuff, and we were open to learning from them as well."

Manilla and his soldiers also got the chance to see the sights and soak in some culture during the weekends, he said. His soldiers got the chance to "see how their nation was formed and what they've been through in the past 50 or so years," he said.

One of their trips took them to the Ninth Fort in Kaunas, Manilla said.

The fort originally was built as a defensive fortress in 1901-1913, according to a website about the fort. During the Nazi occupation, more than 50,000 people were executed there, including more than 30,000 Jews and more than 10,000 foreigners.

"The Russians had occupied it, the Germans had occupied it, there was a lot of culture in it," Manilla said. "We went to places that were 100 to 200 years old."

The soldiers also were treated to a special viewing of Brad Pitt's World War II tank movie, "Fury," Manilla said.

His time in Lithuania was rewarding, he said.

"We got a chance to work with not only the Lithuanians but the British and Hungarians, and we got to go force-on-force with our other NATO partners," he said. "To me that was the best training, understanding how other countries operate as well as them understanding how we, as an infantry platoon, operate."

Adding aviation, tanks

In addition to troops on the ground, the Army also is working on the possible rotation of aviation capabilities into Europe, Hodges said.

"The demand for aviation here is not going down; it's actually increasing," he said. "The Army is looking at rotational aviation to help us maintain our aviation capabilities. Army aviation is so valuable, and the demand is going to at least stay the same, if not increase."

The Army also is building the equipment it has in the European region, with major changes slated for 2015.

In 2013, the Army shipped its tanks and Bradleys back to the United States, marking the end of an era that began 70 years ago during World War II. At its peak, Germany was home to 20 U.S. armored divisions, or about 6,000 tanks.

Soldiers fire TOW missiles Nov. 20 at Grafenwoehr, Germany, during the live-fire portion of the multinational training exercise Combined Resolve III.

Photo Credit: Capt. John Farmer/Army

Today, the Army has a European Activity Set that contains about a battalion's worth of heavy equipment, including 29 Abrams tanks and 33 Bradleys. This set is meant to be used by troops coming into the region from the United States.

Plans call for the equipment set to grow to that of an armored brigade by the end of 2015 — that's about 150 tanks and Bradleys and 24 155mm howitzers for three combined arms battalions, an armored reconnaissance squadron and enablers.

What remains to be determined is where this equipment will be stored, Hodges said.

Some equipment could be stationed in Germany, while the rest is stored in the Baltics, or all of it could be in one location, he said.

"I think of the Operation Atlantic Resolve area, from Estonia down to Bulgaria, as one big maneuver box," Hodges said. "The brigade commander, I would want him to be able to move units around to achieve the strategic effects of assurance and deterrence."

The soldiers from 1st BCT, 1st Cavalry fell in on the existing activity set, but they also shipped some of their own tanks and Bradleys when their mission grew from Combined Resolve III to also include Operation Atlantic Resolve, DiGiambattista said.

About 2,000 soldiers, including two combined arms battalions, from the Fort Hood, Texas, brigade deployed to Europe. They brought with them 10 tanks, 30 Bradleys and 20 Strykers.

"When you bring an armored force, you really show the commitment of the United States of America," DiGiambattista said. "To train with the Latvians and Poles and do combined live-fires where they were working with our tanks and Bradleys for the first time really showed U.S. resolve."

The experience also gave his junior leaders valuable hands-on experience, DiGiambattista said.

"We put four companies into those four nations, so we ended up with junior leaders working in pretty significant areas," he said. "I think the opportunity for those captains and first sergeants and field-grade officers to learn about higher level engagements, whether it was at the embassy or the host militaries, was a pretty exceptional experience."

The deployment also gave his soldiers the chance to contribute to a significant mission, DiGiambattista said.

"The president has been to the Baltic nations and Poland twice this ye

ar," he said. "Clearly this was important for the nation, and we were able to contribute to that effort. That, for us, was significant."

Staff writers David Larter and Oriana Pawlyk contributed to this report.