US Army and Lithuanian armed forces, as well as authorities, located the missing armored recovery vehicle the next day submerged in a bog under nearly 20 feet of water and thick layers of mud, clay, and sediment. These bogs sometimes run deep, but the depth can be easy to misjudge.

Hundreds of rescue personnel took part in the "highly complex" recovery operation, including a specialized US Navy dive crew able to navigate the murky waters.

More than 30 tons of gravel and a large-capacity pump were used to help drain the swamp-like terrain, which could not support the weight of heavy equipment like excavators and cranes needed to tow the 70-ton vehicle to the surface.

"Not only are we dealing with the terrain, a lot of mud that is over top of the vehicle, but also the fact that it's 70 tons that we're trying to recover out of a swamp or bog," Brig. Gen. John Lloyd, commander of the US Army Corps of Engineers North Atlantic Division, explained in a statement.

So what is the M88 that sank? The M88 recovery vehicle has been a vital asset to the US military since the Vietnam War.

The recovery vehicle's primary role is to tow, extricate, and repair damaged or immobilized tanks and fighting vehicles while under fire. It can also lift and repair damaged turrets and other heavy artillery and clear obstacles during operations on complex terrain, like the peat bog where the American soldiers were found.

After the first M88 was introduced in the early 1960s, the vehicle underwent several upgrades, including a new diesel engine, improved armor, and stronger lifting capabilities.

Introduced in 1997, the third variant, the M88A2 Hercules, is one of the largest armored recovery vehicles used by the US military.

The Hercules was designed with a stronger hoist and increased winching power, allowing it to recover heavier combat vehicles up to 70 tons, like the powerful US-made M1 Abrams tank, which was too heavy for previous M88 models to tow effectively.

Designated as a "heavy recovery vehicle," the new Hercules weighs a whopping 70 tons — about 14 tons heavier than the M88 and M88A1, which were considered "medium recovery vehicles."

The Hercules' steel hull was designed to protect personnel from mines, artillery fragments, and small arms fire. The armored recovery vehicle is also equipped with mounted 12.7 mm heavy machine guns with 1,300 rounds.

Powered by a twin-turbo diesel engine with 1,050 horsepower, the M88A2 can reach speeds of up to 30 mph on varied terrain and on uneven surfaces. Like a tank, it has a tracked chassis.

Global defense company BAE Systems manufactures the M88A2 Hercules, which stands for Heavy Equipment Recovery Combat Utility Lift and Evacuation System.

BAE Systems is also developing the fourth M88 variant, the M88A3 Hercules, intended to eliminate the need for two M88A2 vehicles when recovering heavier modern Abrams tanks.

With upgraded powertrain and suspension units, the modernized heavy recovery vehicle features improved cross-country mobility and maneuverability, as well as an increased towing capacity of up to 80 tons. Last year, the Army began testing the new M88A3's capabilities at Yuma Proving Ground in Arizona.

Amid rising tensions with a belligerent Russia, the US delivered M88s to NATO allies in Eastern Europe, including the Baltic states and Poland, to support real-world operations and joint exercises.

The US soldiers who died during the recent training exercise were stationed in Lithuania as part of Operation Atlantic Resolve, which is a US contingency operation that's aimed at deterring Russian aggression by strengthening NATO forces in the region.

The training area where the four soldiers went missing is located roughly six miles west of the border with Belarus, a close Russian ally.

While Abrams tanks, Bradley infantry fighting vehicles, and Stryker armored vehicles significantly bolster Ukraine's ground forces, one US Army workhorse ensures these armored vehicles and heavy assets stay combat-ready: the M88 armored recovery vehicle.

In October 2022, the US sent eight M88s to Ukraine as part of its military aid package, and in February 2023, the Biden administration sent an additional six unspecified tactical recovery vehicles.

The recovery vehicles play a key role in maintaining Ukraine's mechanized force. They allowed Ukrainian troops to quickly retrieve and repair damaged assets and equipment from the battlefield, making ARVs "high-value targets" for Russian forces, according to UK defense officials.

The M88s were also involved in US-led operations in the Middle East, including Operation Desert Storm, Iraqi Freedom, and Enduring Freedom.

The ARVs recovered Abrams and Bradleys, often navigating harsh desert conditions and rugged, mountainous terrain in Kuwait, Iraq, and Afghanistan.

One M88A2, now on display at the National Museum of the Marine Corps in Virginia, was notably used to topple the statue of Saddam Hussein in Baghdad in 2003.

Hailed for its tank-killing capabilities and operational flexibility, France sent Ukraine more than three dozen AMX-10RC armored vehicles to bolster its frontline defenses.

Developed in the late 1970s, the so-called "wheeled tank" was designed for reconnaissance and close-fire support. It was used to scout and identify enemy positions while armed to rapidly fire on hostile threats.

The 30-foot, 18-ton armored vehicle has a range of about 500 miles and travels at speeds of about 37 mph on roads and about 9 mph off-road; it has less off-road maneuverability than tracked vehicles like tanks.

After about a decade of service, France stopped producing the AMX-10RC in favor of more advanced combat vehicles like the ERBC Jaguar, an armored scout vehicle armed with two anti-tank missiles and a 40mm gun.

The AMX-10 has a turret with two 7.62mm machine guns and a 105mm cannon, which is powerful enough to destroy a tank at close range.

Ukrainian forces operate both the AMX-10RC and AMX-10RCR, an improved variant of the armored vehicle featuring upgraded ceramic armor, more advanced optronics systems like thermal sights, and a self-defense system that automatically launches smoke grenades and decoys.

The AMX-10 can carry a crew of four people — a machine commander, a gunner, a loader, and a driver.

It can carry up to 38 shells for its main gun and 4,000 rounds for its machine guns. An AMX-10 crew featured on Ukraine's state-run Army TV said the vehicle's rate of fire can range from five to 12 rounds per minute, depending on the loader's efficiency.

Ukrainian troops initially struggled to integrate the AMX-10RC into their frontline strategy. The vintage armored vehicle's light aluminum armor left it vulnerable in high-intensity conflict zones, especially against Russia's more advanced artillery and defense systems.

Instead, Ukrainian forces took advantage of the wheeled platform's maneuverability and repurposed the armored fighting vehicles as self-propelled artillery that could engage hostile targets from afar.

Army TV, run by the Ukrainian Defense Ministry, captured the AMX-10's capabilities in action in a video posted last week.

While filming a segment aboard the AMX-10, the Ukrainian soldiers and the television crew came under attack by a Russian drone. The personnel and TV crew weren't harmed, and the vehicle was not damaged.

In September, thousands of Ukrainian troops — most of whom had only a few weeks of basic training — were sent to eastern and southern France to hone their skills on the battlefield against Russia.

Named "Anne of Kyiv" after the former Ukrainian princess who became a queen of France, French authorities said the brigade will eventually consist of up to 4,500 troops specializing in infantry battalions, engineering units, artillery teams, and other roles.

The newly trained brigade is set to be armed with various French-supplied military assets and weaponry, including armored vehicles, artillery cannons, and anti-tank and antiaircraft missile systems.

A military task force of about 1,500 French soldiers trained Ukraine's troops on effective fighting strategies and skills and how to use and maintain the French-supplied equipment. Over 2,000 Ukrainian soldiers completed the training in France in late November.

"They have improved a lot," a French colonel told the Associated Press. "Now, they are able to fight. They are able to maneuver. They are able to use the different specialists and to use the different equipment they will have on the battlefield."