Belarusian officials say Russian fighter jets have arrived to help patrol Belarus's borders, as part of a new joint military effort.
The arrival of the Sukhoi jets, announced on September 8, comes a day ahead of a critical meeting between Belarusian leader Alyaksandr Lukashenka and Russian President Vladimir Putin in Moscow.
The Russian jets "arrived at the Baranovichi airfield to form a joint training center for the air force and air defense forces of Belarus and Russia," the Belarusian Defense Ministry said in a statement .
The statement did not say how many jets arrived, or give further details.
The jets' arrival also comes two days ahead of major military exercises involving thousands of troops from both countries -- exercises that have prompted public statements of concern from some NATO countries.
Lukashenka and Putin's meeting comes with growing speculation that the two leaders could finalize an integration of the two countries planned decades ago, something known as the union state.
The project would be a major step toward reuniting the two countries, but also could undermined Belarus's sovereignty, something Lukashenka has strenuously resisted for years.
But Lukashenka has been increasingly isolated since a presidential election last year in which he claimed reelection to a sixth term. The vote was condemned by Belarus's opposition as rigged, and prompted months of street protests that Belarusian security forces have harshly cracked down on. Western governments have ignored Lukashenka's claim to reelection.
In recent weeks, Belarusian officials have given signals that Lukashenka might finally be moving to sign the last of a series of "road maps" that would finally lead to the union state.
Earlier this month, Lukashenka said Russia would soon deliver a huge military hardware consignment to Belarus, including aircraft, helicopters, and air-defense systems.