NATO Secretary General Jens Stoltenberg will visit a US-led NATO battalion in Poland on Friday amid concern on the alliance's eastern flank over a huge Russian military exercise in neighbouring Belarus next month.
Stoltenberg will hold talks with Polish President Andrzej Duda in Warsaw on Thursday before travelling to the NATO base in the northern village of Orzysz, Tomasz Szatkowski, Poland's deputy defence minister, told local media on Tuesday.
The multinational battalion stationed in Orzysz is one of four deployed by NATO this spring to Poland and the Baltic states of Estonia, Latvia and Lithuania to reassure its easternmost allies, which have been unsettled by Russia's frequent military exercises near the region in the wake of its 2014 annexation of Crimea from Ukraine.
The Orzysz base lies about 100 kilometres (60 miles) from Russia's Kaliningrad exclave and a stone's throw from the Suwalki Gap, a strategically important land corridor critical to the security of the Baltic states.
The gap, a 65-kilometre stretch of border with Lithuania, is sandwiched between Kaliningrad and Belarus.
Military strategists say it is the Achilles' heel of NATO's eastern flank, since its capture would amputate the alliance's three Baltic members and so shatter its credibility.
Formerly Soviet-ruled Baltic states worry they may be next to face pressure from the Kremlin, which is why they are casting a wary eye on September's "Zapad 2017" (West 2017) Russian military drills in Belarus, which borders Latvia, Lithuania and Poland.
Lithuania's Defence Minister Raimundas Karoblis warned in June that Moscow might use the manoeuvres as cover for an aggressive troop buildup on NATO's eastern flank.
"Putin would like to test NATO... and probably the best area for him to test is the Baltics," Karoblis told AFP.
He said his government estimated that 100,000 Russian troops would be involved in the exercise, while official Russian figures quoted in Polish media reports peg the number of troops at 12,700.
Moscow has invited representatives of all three Baltic states to observe the drills.
Stoltenberg said in July that Russian officials had given the alliance figures for the Zapad war games but he declined to make them public, saying it was up to Moscow to do so.
He added that the alliance had held "frank" talks with Moscow on how to avoid dangerous misunderstandings over issues such as exercises.
General Ben Hodges, commander of US ground forces in Europe, said last week that "Poland has become for the United States Army the centre of gravity for everything that we're doing in terms of deterrence" regarding Russia.