U.S. Marines and sailors recently teamed with other NATO allies during a major show of force in Ukraine amid growing concerns about a Russian military plus-up on the Crimean border.

Troops from 16 nations completed Exercise Sea Breeze, which was held just a couple of hundred miles from the Crimean Peninsula, on July 30. U.S. military officials tout the annual air, land and maritime exercise as a way to enhance interoperability and strengthen regional security in a volatile region marked by the 2014 Russian incursion of Crimea and continuing civil war in Ukraine, which borders Russia.

"This year's Sea Breeze exercise is definitely a signal to Russia," said Bryan Clark, a senior fellow at the Center for Strategic and Budgetary Assessments who previously served as special assistant to the chief of naval operations and director of his Commander's Action Group. "It is in part to demonstrate to Russia that U.S. and NATO forces will still operate adjacent to Russian territory and forces despite Russia's protests. Also, the situation in eastern Ukraine is reaching a new boiling point and may result in a more intense conflict erupting again this fall. If followed up with clear statements from the U.S. about how the U.S. will respond to new Russian aggression, exercises like this are a way to indicate to Russia American resolve."

160727-M-PJ210-001 BAZAR'YANKA, Ukraine (July 27, 2016) U.S. Marines with 22nd Marine Expeditionary Unit (MEU) and Ukrainian soldiers travel in an assault amphibious vehicle during Exercise Sea Breeze 2016, July 27. 22nd MEU, deployed with the Wasp Amphibious Ready Group, is conducting naval operations in the U.S. 6th Fleet area of operations in support of U.S. national security interests in Europe. (U.S. Marine Corps photo by Cpl. Chris Garcia/Released)

U.S. Marines with 22nd Marine Expeditionary Unit and Ukrainian soldiers travel in an assault amphibious vehicle during Exercise Sea Breeze 2016. Since Ukraine has nothing like the AAV, its troops had to learn how to open the hatch and get secure in their seats.

Photo Credit: Cpl. Chris Garcia/Marine Corps

In addition to signaling resolve, the exercise served as a way to practice the kind of amphibious operations that could be used to suppress or isolate Russian naval forces in Crimea and Sevastopol, he said.

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"Showing the ability to execute this kind of operation, even if the U.S. doesn't want to do it, will help remind Russia that their forces outside Russia may be vulnerable to attack," Clark said.

This year’s exercise included 26 ships , 20 aircraft, 140 vehicles, and 4,000 international troops from the U.S., Ukraine, Bulgaria, the United Kingdom, Greece, Georgia, Italy, Spain, Lithuania, Moldova, Norway, Poland, Romania, Turkey, Sweden and Finland.

The U.S. Navy sent two ships to participate for the first time: the amphibious dock landing ship Whidbey Island and guided-missile destroyer Ross. About 205 members of Battalion Landing Team, 1st Battalion, 6th Marines — deployed with the 22nd Marine Expeditionary Unit — also participated.

During the exercise, Marines and sailors teamed with more than a dozen Ukrainian troops for a mock amphibious landing. Fifteen amphibious assault vehicles covered nearly 4 nautical miles to Odessa, then moved about 13 miles by land to establish a blocking position at two separate bridges in Bazar’yanka, said 2nd Lt. Marco Valenzuela, a Marine spokesman.

It was the first time the MEU used AAVs to transport the Expeditionary Fire Support System, a 120mm mortar used to support infantry units with indirect fire support. Since Ukraine has nothing like the AAV, basic matters such as opening the hatch and getting secure in the seat proved challenging, said Cpl. Trenton Murry, an AAV crew chief with Charlie Company who carried three Ukrainians in the back of his hog.

"The biggest challenge was the language barrier," he said. "It was difficult at first trying to convey what you wanted accomplished, but we did find out that their basic hand and arm signals for infantry movements are quite similar to ours."

Despite the communication challenges, the exercise allowed the grunts to step outside of their comfort zone and flex their capabilities, said Maj. Jeffrey Erb, Charlie Company's commander.

"We tried a few new things," he said. "We took the opportunity to integrate our heavy mortar systems into the AAVs and it worked out really well. It definitely opens up that option for us in the future."

In addition to the amphibious landing, members of Fleet Anti-Terrorism Security Team Company Europe teamed with Seabees from Naval Mobile Construction Battalion 133 and Ukrainian marines with their 36th Engineering Regiment to learn how to use triple strand concertina wire in defensive positions. Ukrainian troops also conducted their first helocast, jumping 20 feet from a helicopter into the open ocean.

"The threats and challenges in which our military forces have to deal with these days are much wider than they used to be," Ivanna Klympush-Tsintsadze, vice prime minister of Ukraine for European and Euro-Atlantic Integration, said at the ceremony that opened the exercise. " The capability of the military forces is not only about numbers of personnel or the quality or quantity of armaments, but it about military professionalism."

The Marines and sailors of the Whidbey Island hosted a closing ceremony aboard the ship.

The 22nd MEU deployed in late June as part of the Wasp Amphibious Ready Group, and is currently in the U.S. 6th Fleet area of operations. The MEU is comprised of Battalion Landing Team 1st Battalion, 6th Marines, Combat Logistics Battalion 22, Marine Medium Tiltrotor Squadron 264 (reinforced), and the MEU Headquarters Command Element. Additional embarked units include Navy Beach Group (NBG) 2 with detachments from Assault Craft Unit 2, ACU 4, Beachmaster Unit 2, Tactical Air Control Squadron 22, Fleet Surgical Team 2, and Helicopter Sea Combat Squadron 22.

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Lance M. Bacon is senior reporter for Marine Corps Times. He covers Marine Corps Combat Development Command, Marine Corps Forces Command, personnel / career issues, Marine Corps Logistics Command, II MEF, and Marine Forces North. He can be reached at lbacon@marinecorpstimes.com.