As Ukraine Pushes Into Russia, Its Next Steps Are Unclear

More than two weeks into Ukraine’s incursion into western Russia, Ukrainian politicians have begun talking about establishing a buffer zone there. But how much farther Ukraine might try to advance into Russia, and how long it plans to stay, is unclear, U.S. officials said.

Ukrainian forces have pushed out in different directions after quickly breaking through thinly manned border defenses early this month. They have broadened their incursion wherever they find the least resistance, setting the contours of what could be a defensible buffer zone to protect Ukrainian towns and villages, which President Volodymyr Zelensky now says is a primary objective of the attack.

After the first week of fighting, Ukraine claimed to control almost 400 square miles of Russian territory — an area roughly the size of Los Angeles.

But American officials are not convinced that Ukraine intends to hold its position in Russia long term. Ukrainian forces have not been digging the kind of extensive trenches necessary to protect soldiers and equipment from enemy fire, if Russia musters enough firepower to repel the attack. They have not been laying minefields to slow down a counterattack, nor have they constructed barriers to slow down Russian tanks, the officials say.

“What the war has shown us so far is that the way to slow a military down is through ‘defense in depth,’” said Seth G. Jones, a senior vice president with the Center for Strategic and International Studies, in a reference to the strategy of using multiple layers of defensive positioning. “If they are not defending territory with a mixture of trenches and mines, it is going to be virtually impossible to hold territory.”

And the more territory Ukraine captures, the greater the challenge it