LUGANSK, May 1. /TASS/. Russian troops are steadily advancing in the Sumy Region, while the Ukrainian military is building fortifications in haste, Russian Military Expert Andrey Marochko told TASS.

"As far as the Sumy area is concerned, our troops are steadily advancing there, while the enemy is defending," he said.

"I would like to note that they have been constructing defense lines and fortifications very actively now," the expert added.