A Ukrainian defense official says Russian forces could launch an offensive in the eastern Ukrainian regions of Kharkiv and Sumy in late May or early June.

Major-General Vadym Skibitsky is the deputy chief of Ukraine's military intelligence agency. He gave his view on Russia's invasion of Ukraine in an interview released on Thursday by Britain's Economist magazine. Friday marked 800 days since the invasion began.

Skibitsky said the likelihood of the Russian assault depends on the situation of the battlefield. He said the size of Russian forces deployed along the border indicates they will fall short of seizing major Ukrainian cities such as Kharkiv, the country's second largest city located in the Kharkiv region.

Currently, intense fighting continues in Ukraine's strategic stronghold of Chasiv Yar in the eastern region of Donetsk.

The regional governor spoke in a TV program on Wednesday. He said the city's population, which was 12,500 before the invasion, has been dramatically reduced. He said the city's last remaining 682 residents have been living in very difficult conditions, without water or power for over one year and with poor access to humanitarian aid.

Skibitsky said the fall of Chasiv Yar is only a matter of time, but will not happen as early as today or tomorrow. He said what is important are stockpiles and supplies.

Observers say the focus is on how new military assistance from the United States will impact the situation on the battlefield.