WASHINGTON

Russian President Vladimir Putin will likely engage in an increasingly brutal military campaign in Ukraine as his forces fail to meet successes he originally envisioned, the CIA director said Tuesday.

William Burns told the House Intelligence Committee that Putin is "angry and frustrated" by his lack of success on the battlefield where Ukrainian forces continue to mount "fierce resistance" that has led to Russian military casualties being "far in excess" of what the Russian president anticipated.

"The challenge that he faces, and this is the biggest question that’s hung over our analysis of his planning for months now," said Burns, "is he has no sustainable political endgame in the face of what is going to continue to be fierce resistance from Ukrainians.”

"Where that leads, I think, is for an ugly next few weeks in which he doubles down, as I said before, with scant regard for civilian casualties, in which urban fighting can get even uglier, cause the one thing I’m absolutely convinced of ... is that the Ukrainians are going to continue to resist fiercely and effectively," he added.

Russia's war on Ukraine, which began Feb. 24, has drawn international condemnation, led to financial sanctions on Moscow, and spurred an exodus of global firms from Russia.

The US has determined "with low confidence" that between 2,000 and 4,000 Russian troops have been killed during the Kremlin's nearly two-week campaign, Defense Intelligence Agency Director Scott Berrier told the committee.

At least 406 civilians have been killed and 801 injured in Ukraine since the beginning of the war, according to the UN, which said conditions on the ground make it difficult to verify the true number.

Some 2 million people have also fled to neighboring countries, said the UN refugee agency.