Russia and Belarus launched a major joint military exercise along NATO’s border on Friday, September 12, 2025, involving training in both nations as well as in the Baltic and Barents seas, the Russian Defence Ministry said.

The "Zapad-2025" exercise, a show of strength by Russia and its close ally, is taking place at a moment of high tension in the Russia-Ukraine war. It comes only two days after Poland, with support from NATO allies, shot down suspected Russian drones that entered its airspace.

The Zapad or "West" exercise had been scheduled before the drone incident, for which Russia denied responsibility.

"The objectives of the drills are to improve the skills of commanders and staffs, the level of co-operation and field training of regional and coalition groupings of troops," the Defence Ministry said on Telegram.

In the first stage, troops will practice repelling an attack against Russia and Belarus, which together form what is known as the Union State.

The second stage will focus on "restoring the territorial integrity of the Union State and crushing the enemy, including with the participation of a coalition group of forces from friendly states," the Ministry said.

Kremlin spokesman Dmitry Peskov said on Thursday, September 11, 2025, that the drills, including those near the Polish border, were not directed against any other country.

Still, the drone incident over Poland this week was seen in the West as a warning to NATO and a test of its response. Western countries described it as a deliberate provocation by Russia, something Moscow rejected.

A senior Russian diplomat in Poland said the drones had come from the direction of Ukraine. Russia’s Defence Ministry confirmed its drones had carried out an attack in western Ukraine, but insisted it had not planned to strike any targets in Poland.

U.S. President Donald Trump said Russia’s drone incursion into Poland might have been a mistake.

"I'm not happy about anything to do with the whole situation, but hopefully that's going to come to an end," Trump told reporters before boarding Marine One on Thursday, September 11, 2025.

Even before the drone incident, Polish Prime Minister Donald Tusk had described the upcoming "Zapad" manoeuvres as "very aggressive" and announced that Poland would close its border with Belarus at midnight on Thursday, September 11, 2025.

Belarus also borders NATO members Lithuania and Latvia. Lithuania said it was protecting its border because of the military exercise.