Ukraine has deployed 8,500 extra troops to its border with Belarus amid fears Minsk may send migrants to its southern neighbour.
It comes amid a crisis on the Poland-Belarus frontier, which Warsaw claims has been instigated by Belarus leader Alexander Lukashenko.
Poland alleged Lukashenko has flown in migrants from the Middle East and sent them to the EU's eastern borders to destabilise the bloc.
It's claimed the action is retaliation for EU sanctions on Belarus over a crackdown on dissent following a disputed presidential election.
Now Kyiv fears migrants will be sent to its border with Belarus. It says troops will work with police to tighten checks in the area.
"Aviation and drones will also be actively used for patrolling and monitoring," a spokesperson for Ukraine's State Border Service said.
The government has put €7 million towards the operation.
"The funding will be allocated from the reserve fund of the state budget and directed to the units of the Ministry of Interior and the Ministry of Defense to strengthen the protection of the state border on the Ukrainian-Belarusian section and eliminate the threat of an emergency situation of a social nature," Ukraine's Ministry of Economy said in a statement.
Kyiv is also worried that the border with Belarus -- a close Russian ally -- could be used by Moscow to stage a military assault.
The head of Ukraine's military intelligence told the Military Times outlet this weekend that Russia had more than 92,000 troops massed around Ukraine's borders and was preparing for an attack by the end of January or the beginning of February.
Moscow has dismissed such suggestions as inflammatory and complained about what it says is increasing activity in the region by the NATO alliance.
The OSCE special representative Mikko Kinnunen said in a statement that monitoring teams reported on damage to civilian houses and infrastructure on both sides of the conflict in eastern Ukrainian regions caused by heavy weapons.
"The average number of daily ceasefire violations has exceeded the figure before entering into force of the measures to strengthen the ceasefire in July 2020," he said.