BORISOVSKY TRAINING GROUND, Belarus and LONDON — Russia put on a display of firepower as part of its major military exercises in Belarus on Monday, with neighboring NATO nations on alert amid some of the highest tensions in Europe since Moscow began its full-scale invasion of Ukraine in February 2022.

Around 7,000 troops are taking part in the exercises, which are being held at locations in Belarus, as well as in Russia’s Kaliningrad Baltic exclave and in the Baltic and Barents seas.

On a firing range ringed by forest at the Borisovsky Training Ground in central Belarus, ABC News and other media watched Russian and Belarusian aircraft, helicopters, tanks and artillery unleash barrages as part of a mock battle against fictitious Western forces.

Warplanes dropped powerful bombs, sending smoke plumes rising into the air, and intense tank and tracer fire flew across the field.

Drones were also heavily involved, a reflection of how the war in Ukraine is altering Russia’s military. Reconnaissance, kamikaze FPV drones and bomber drones all took part, as did ground-based robots used for recovering wounded troops.

The drills come less than a week after around two dozen Russian long-range drones crossed into Poland, which shares a 260-mile border with Belarus and a 130-mile border with Kaliningrad. At least three drones were shot down by responding Polish F-16 and Dutch F-35 fighters, Warsaw said.

The incursion was by far the largest-ever of Russian drones into NATO airspace, a move that has alarmed allied countries and fueled fears the war is escalating and spreading. Polish and allied officials have said that the incursion was intentional.

Zapad is expected to host demonstrations by Russia’s nuclear forces, launches of Zircon hypersonic cruise missiles and operations related to Russia’s Oreshnik intermediate-range ballistic missile, which is a nuclear-capable weapon and has been used to strike Ukraine.

NATO countries are on heightened alert. Poland has closed its border and airspace with Belarus and deployed 40,000 troops in response.

Lithuania and Latvia have also closed their airspace along their Belarusian borders for the duration of the drill.

The Zapad drills are taking place amid an apparent thaw in U.S.-Belarusian relations. Last week, U.S. presidential envoy John Cole visited Belarus where he announced the lifting of American sanctions on the state-owned airline Belavia and stated the intention to re-open the shuttered U.S. embassy in Minsk.

Allied officials were present at Monday’s exercises. Two U.S. military attachés attended, with military observers from fellow NATO nations Turkey and Hungary also on site.

The Zapad — meaning “West” — exercises simulate a defense against an attack on Belarus by Western forces.

The last time Russia held these exercises in 2021, it used them as cover to build up its troops to invade Ukraine months later. The ill-fated Russian thrust toward Kyiv was launched from Belarus, reaching the city’s suburbs before collapsing under the strain of supply shortages and Ukrainian counter attacks.

This year’s installment is drastically diminished. Russia is unable to spare manpower from Ukraine, where its forces are prosecuting grinding offensives at multiple points along the front. Only a few thousand Russian troops are believed to be taking part in this week’s drills.

The 2023 exercises were canceled entirely under the strain of Russia’s war.

Russia this year may put the focus on nuclear weapons, including drills relating to its Oreshnik missile.

Russian and Belarusian officials have framed the drills as purely defensive maneuvers.

Kremlin spokesperson Dmitry Peskov told reporters last week that the Zapad drills are not directed against “any third country.”

“This is about continuing military cooperation and practicing coordination between two strategic allies,” he told reporters at a briefing. “We will continue along this course, which is by no means a secret to anyone.”

Still, Peskov told reporters on Monday as the drills commenced that NATO “is fighting with Russia — that is obvious and requires no additional evidence.”

“NATO is de facto engaged in this war,” both “indirectly” and “directly” with its aid to Ukraine, he added.

The exercises appear to hint at Russia’s resolve to maintain its military pressure on Ukraine and on Kyiv’s foreign backers, despite the Kremlin’s claimed readiness to engage in U.S.-led peace talks.

U.S. President Donald Trump again pushed back any threat of sanctions on Russia over the weekend, saying he will only impose new measures so if NATO countries stop buying Russian oil and heavily tariff China.

One month after his summit with Russian President Vladimir Putin in Alaska, Trump’s proposed in-person meeting between Putin and Ukrainian President Volodymyr Zelenskyy has yet to come to fruition.

Ukrainian officials, meanwhile, are continually urging the White House to deliver on its threat of new sanctions on Moscow.

Trump also raised concerns along NATO’s eastern frontier when he said Russia’s drone incursions into Poland “could have been a mistake” — a suggestion quickly contested by Warsaw.

“We would also wish that the drone attack on Poland was a mistake. But it wasn’t. And we know it,” Polish Prime Minister Donald Tusk wrote on social media.