In the south, Russian mortar and artillery fire hit several towns, including the regional capital, Kherson, which Russian forces abandoned in November.
Russian troops are active at night - we are in great need of night vision equipment."
Western countries have produced a steady supply of weapons to Ukraine since Russian forces invaded last Feb. 24 but Zelenskiy and his government are insisting they need tanks.
The OSCE is the world's largest regional security organisation, consisting of 57 states, such as the United States, all European states, including Russia and all states of the former Soviet Union.
The U.S. State Department estimated last year that between 900,000 and 1.6 million Ukrainian citizens, including 260,000 children, have been forcibly deported into Russian territory.