The U.S. has deployed 12 A-10 Warthog planes to Romania as part of a theater-security effort to counter Russian aggression in Ukraine – all while debate over whether to retire the close-air support platform rages on in Congress and the Pentagon.

"The 354th Expeditionary Fighter Squadron forward deployed 12 A-10 Thunderbolt II aircraft and approximately 200 Airmen and support equipment from Spangdahlem Air Base, Germany to Campia Turzii, Romania over the weekend," Pentagon spokesman James Brindle said.

The deployment marks the first ever deployment of A-10s to Romania, he added.

"The unit will conduct training alongside our NATO allies to strengthen interoperability and demonstrate U.S. commitment to the security and stability of Europe," Brindle explained.

The deployment comes as the future of the A-10 platform lingers in a haze of uncertainty. The Air Force hopes to retire the planes and save more than $4 billion. Service officials say the A-10s will be fully divested from the inventory by 2019.

"We proposed their divestiture across the next four years in our 2016 budget submission. That plan would include them to continue to deploy until we’ve completed divesting the fleet," Maj. Erika Yepsen, Air Force spokeswoman, told Military.com.

Air Force officials emphasize that the service remains committed to providing close air support for the joint force.

"While the A-10 provides outstanding close air support, it is not the only aircraft that performs this mission. However, faced with difficult budget choices, divestiture of the A-10 presents the least risk to balancing capability, capacity and readiness," Air Force spokesman Lt. Col. Chris Karns, told Military.com.

At the same time, many lawmakers and A-10 proponents have pushed back on this plan, promising to add money back to the A-10 program during the upcoming 2016 budget bill mark-ups.

A-10 advocates swear by the aircraft’s unique ability to withstand ground fire. Several prominent lawmakers, to include Senate Armed Forces Committee chairman Sen. John McCain, R-Ariz., and Sen. Kelly Ayotte, R-N.H., argue vigorously for the preservation of the A-10 platform.

Overall, Pentagon officials described the A-10 deployments as part of NATOs Operation Atlantic Resolve strategy aimed at, among other things, projecting and deploying force against Russia

"Operation Atlantic Resolve will remain in place as long as the need exists to reassure our allies and deter Russia from regional hegemony," he said.

The A-10s will remain deployed in Romania for at least about 90 days to conduct various training events through Eastern Europe.

"These rotational forces really bolster our capability. They underscore our commitment to European security and send a clear message that the US is serious about the stability and security of Europe," Lt. Col. David Westover, U.S. European Command spokesman, told Military.com.

Other elements of the NATO operation include efforts to deploy more military equipment across the region and use of the Army’s 3rd Infantry Division to train land forces in Poland, Estonia, Latvia and Lithuania.

Over 100 vehicles including Abrams tanks and Bradley Fighting Vehicles were recently offloaded in Riga, Latvia. The equipment is slated to be shipped to the Baltic states with the remaining equipment awaiting offload in Bremerhaven, Germany, Brindle said.

"Approximately 120 pieces of equipment will be left behind after 3ID rotates and be relocated to Germany to support the planned expansion of U.S. Army Europe's ‘European Activities Set’ from a heavy battalion to a heavy brigade-sized equipment set," Brindle said.

Also, at the end of March, a US Patriot missile battery participated in joint exercises with the 3rd Warsaw Air Defense Missile Brigade. The US Army Detachment was composed of 100 soldiers and 30 vehicles, Pentagon officials said.

The 2015 defense bill provides up to $1 billion in funding for Operation Atlantic Resolve, an effort which includes a wide range of activities spanning from F-16s training with the Estonian Air Force and various U.S. Naval deployments in the Black Sea. The USS Cole, a guided missile destroyer, conducted joint training exercises in the Black Sea with the Romanian Navy in February of this year.

The Atlantic Resolve strategic effort includes an additional $46 million in security assistance funding to train and equip the Ukrainian National Guard. Some of the equipment provided includes counter-mortar radars, body armor, helmets, vehicles, night and thermal vision devices along with radios, patrol boats, rations and tents, Pentagon officials said.

-- Kris Osborn can be reached at kris.osborn@military.com