Ukraine says its troops are advancing to retake territories in the east and south of the country, and that Russian forces are on the defensive, but are mounting attacks on the capital region and elsewhere.

Ukrainian President Volodymyr Zelenskyy spoke Monday about the country's counteroffensive. He said Ukraine has not lost any positions, but have only liberated ones. He added the Russians have suffered losses.

The US think tank Institute for the Study of War said in its analysis on Monday, "Ukrainian forces conducted counteroffensive operations in at least three sectors of the frontline and made gains on June 19." The institute also said Ukrainian troops have made advances around Bakhmut in the eastern region of Donetsk and the southern region of Zaporizhzhia.

Ukraine's Commander-in-Chief Valerii Zaluzhnyi posted a video online that he claims shows his visit to a frontline position. He said Russian forces are trying to prevent Ukrainian troops from advancing by setting up fortifications with dense minefields.

Ukraine's deputy defense minister Hanna Maliar said Tuesday that Ukrainian troops are having difficulty advancing because Russia is deploying all of its forces to stop the offensive. She also said Ukrainian troops are advancing in the south, while Russia is concentrating its forces in the east.

Ukrainian air force officials said Russia conducted an overnight attack with 35 Iranian-made drones but Ukrainian forces destroyed 32 of them. It added that the main target was the Kyiv region.

Officials of the western area of Lviv reported that the region's infrastructure was attacked by drones.

Observers say Russia is conducting attacks on areas away from the frontlines in an apparent attempt to weaken Ukraine's offensive in the southern and eastern areas of the country.