Ukrainian forces hold drills in Chernobyl Exclusion Zone

Machine gun fire echoed through the abandoned buildings of Pripyat in the Chernobyl Exclusion Zone, as Ukrainian National Guard troops staged urban combat exercises on Friday.

The live-fire training - carried out in one of the most radioactive places on earth - came as warnings of a possible Russian invasion.

Moscow has deployed over 100,000 troops along Ukraine's border, including sending troops to Belarus, which lies just 10 kilometers 6 miles north of the Ukraine border for joint drills.

The deserted streets and apartment blocks of Pripyat - empty since residents were evacuated after the 1986 nuclear reactor disaster, has made an ideal training ground for Ukraine's forces.

Troops in winter camouflage practiced clearing armed attackers from buildings, targeted mortar fire and took on snipers in urban conditions.

Emergency service workers staged evacuations — a speaker on a drone telling residents to clear out — and fought fires caused by fighting.

Exclusion zones have their own risks, and conducting exercises inside the exclusion zone has its own risks.

Ahead of the training, the first of its kind in Pripyat, workers with Geiger counters had to scan the route to check there were no radioactive hot spots.

Litva said it had all been checked and it doesn't present a danger, as he clutched his automatic rifle to his chest.

Some Western leaders insist the threat from Russia's massed forces is real and urgent, but authorities in Kyiv have cautioned against panic. Ukraine's defense minister Oleksiy Reznikov played down the possibility of an incursion by Russian forces sent to Belarus for joint drills.

While the U.S. has said their number could reach 30,000, Reznikov said that the number of thousand Russians currently over the Belarusian frontier was not enough to attack.

He pointed out to difficult terrain as a major obstacle and the threat from radiation if they tried to push through the exclusion zone toward the capital Kyiv.

This area is very hard to get through — forests, swamps, rivers — it is complicated enough to move by foot if you don't have a tank, Reznikov told reporters, who had been ferried into the exclusion zone on a press tour to see the exercises.

There are still highly radioactive areas on the route from Belarus after the disaster. Ukraine s interior minister Denys Monastyrskiy said that security had been stepped up around all nuclear reactors - including the Chernobyl site, now covered by a mammoth protective sarcophagus.

Monastyrskiy said that they were absolutely certain that the nuclear plant in Chernobyl is not under threat.

The National Guard troops in Pripyat were not trained to counter a Russian invasion.

They were instead preparing for the threat from unreformed infiltrators who might seize buildings and cause unrest across the country.

That happened when Russia seized the Crimean peninsula in 2014 and began causing a separatist conflict in the east of Ukraine.

Ukraine s authorities insist that type of internal destabilization remains their biggest concern.

Monastyrskiy said that we have to show our readiness to react to all events.