NATO Secretary General Jens Stoltenberg expressed concern that Russia continues to build up military power around Ukraine and has sent more troops and military equipment to Belarus than at any time in the past 30 years, AP reports.

“Over the last days, we have seen a significant movement of Russian military forces into Belarus. This is the biggest Russian deployment there since the Cold War,” Stoltenberg told reporters at NATO headquarters in Brussels.

According to him, "the number of Russian troops in Belarus is likely to increase to 30,000 people with the support of special forces, modern fighters, Iskander short-range ballistic missiles and S-400 surface-to-air missile defense systems."

“So, we speak about a wide range of modern military capabilities. All this will be combined with Russia’s annual nuclear forces exercise, expected to take place this month,” Stoltenberg said.

He called on Russia to de-escalate and echoed Western warnings that any further Russian aggression will have serious consequences and a heavy cost.

Stoltenberg also welcomed President Joe Biden's decision on Wednesday to send 2,000 US-based troops to Poland and Germany and move another 1,000 troops from Germany to Romania, demonstrating to allies and adversaries alike Washington's commitment to NATO's eastern flank.

“We are committed to finding a political solution to the crisis, but we have to be prepared for the worst,” Stoltenberg said, and he welcomed other recent offers of troops and equipment from several allies. Russia objects to the troop move and has described it as “destructive.”