Poland and NATO are deploying around 30,000 troops as part of the country's largest military drills of the year, Polish broadcaster TVP World reported on Wednesday.
The Polish Armed Forces are also assembling over 600 tanks, aircraft and missile systems.
The exercises, codenamed "Iron Gate," are taking place at a training ground in Orzysz, just 100 kilometres (62 miles) from the strategic Suwalki Gap, a narrow strip of land near the Russian exclave of Kaliningrad.
They are reportedly intended to demonstrate alliance unity amid rising tensions with Russia.
They also come after Russia's joint military exercises with Belarus, Zapad-2025, ended on Wednesday after running since September 12 just across the border.
The drills also follow a recent suspected Russian drone incursion in the region.
Last week, Poland said that at least 19 drones crossed into Polish airspace when Russia was attacking Ukraine. Russia, however, said the incursion was not deliberate.
