NATO Secretary General Jens Stoltenberg

:: NATO Secretary General Jens Stoltenberg on Friday urged the Kremlin to comply with rules on transparency as Russia geared up for huge military exercises along the alliance’s eastern flank next month.

Stoltenberg, speaking at a joint press conference in Warsaw with Poland’s right-wing Prime Minister Beata Szydlo, urged Moscow to respect international conventions on keeping other countries informed of the maneuvers.

Zapad 2017 (“West“), has stoked alarm in NATO members Poland and the Baltic states, all former members of the Soviet bloc.

It takes place in Belarus, which border three NATO member states, and comes as a more assertive Russia pushes back against what it sees as the alliance’s unjustified expansion into eastern Europe.

“I call on Russia to ensure compliance with its obligations under the OSCE Vienna Document, because predictability, transparency is especially important when we have increased military activity along our borders,” said Stoltenberg.

The Vienna Document requires signatory nations to provide advance information of exercises and to allow observer teams to avoid any dangerous misunderstandings.

Stoltenberg was even more outspoken on Thursday in Italy when he said that “the aggressive behavior of Russia has undermined stability and security in Europe.”

On Friday, he vowed that the alliance would “be watching very closely as this (Zapad) exercise takes place next month” in Belarus, which borders alliance members Latvia, Lithuania and Poland.

Under Vienna Document provisions, maneuvers involving more than 13,000 troops must be notified in advance and be open to observers.

Belarus has said Zapad 2017 involves 12,700 troops, just under the limit, but Lithuania and other critics claim there could be as many as 100,000.

According to NATO, Belarus has invited military liaison missions to attend a special visitors day on its territory, with two alliance experts due to attend.

Russia’s Interfax news agency reported this week that the Belarussian defense ministry had invited observers from seven countries: Ukraine, Poland, Lithuania, Latvia, Estonia, Sweden, and Norway.

Russia has dismissed the concerns over the exercises. “I do not see any reason to be afraid,” deputy defense minister Alexander Fomin told the Rossiya 24 news channel. “Everything, as usual, will be open and friendly.”

The Kremlin has also denied any territorial ambitions and argues that it is NATO that is trying to encircle Russia.

Later Friday, Stoltenberg visited a US-led NATO battalion based in the northeastern Polish town of Orzysz.

The German and Lithuanian presidents meanwhile visited a similar NATO base some 250 kilometers (155 miles) away in Rukla, Lithuania.

NATO deployed four multinational units to Poland and the Baltic states of Estonia, Latvia and Lithuania to reassure its easternmost allies unsettled by Russia’s frequent military exercises near the region following its 2014 annexation of Crimea from Ukraine.

The Orzysz and Rukla NATO bases are both close to Russia’s highly militarised Kaliningrad exclave and the Suwalki Gap, a strategically important land corridor critical to the security of the Baltic states.

The gap, a 65-kilometer (40 miles) stretch of border with Lithuania, is sandwiched between the Russian exclave of Kaliningrad and Belarus.

Military strategists say it is the Achilles’ heel of NATO’s eastern flank since its capture would cut off the alliance’s three Baltic members.

Stoltenberg said Friday that the strong NATO presence near the gap sent a “clear signal” about its resolve to defend its eastern flank, where Russia has ramped up military drills in recent months.

General Ben Hodges, commander of US ground forces in Europe, said last week that “Poland has become for the United States Army the center of gravity for everything that we’re doing in terms of deterrence” regarding Russia.

Aside from leading the NATO force in Orzysz, the US Army set up a new European headquarters in Poland in May to command some 6,000 of its troops deployed in NATO and Pentagon operations across the alliance’s eastern flank since the beginning of the year.