Russia’s attempt to conquer Ukraine could be headed toward a stalemate as heavy casualties and equipment losses take a toll on unprepared Russian forces that have failed so far to achieve any of their initial objectives, Western officials and military experts say.

The front lines have barely moved in more than a week. Russians are being killed or injured at the rate of up to 1,000 a day, according to Western intelligence estimates, and even more according to Ukrainian ones.

Videos of burned-out tanks and abandoned convoys stream constantly on Ukrainian social media accounts, alongside footage of dead Russian soldiers, surrendering Russian soldiers, hungry Russian soldiers stealing chickens from local farmers — and, increasingly, the mangled bodies of Ukrainian civilians dying in missile and artillery attacks.

The ferocity of the Russian assault has only intensified as the advances have slowed, with Russia substituting harsh bombardments of civilian populations for progress on the battlefield. Regular Ukrainians living in cities surrounded, or partially surrounded, by Russian troops are paying the price for a war effort that began to go wrong in the first hours.

But in the absence of substantive progress on the ground and given the scale of the losses being inflicted on its ranks, Russia’s military campaign could soon become unsustainable, with troops unable to advance because they lack sufficient manpower, supplies and munitions, analysts and officials say.

The next two weeks could be critical in determining the outcome of the entire war, they say. Unless Russia can swiftly improve its supply lines, bring reinforcements and bolster the flagging morale of the troops on the ground, its goals may become impossible to achieve.

An assessment Saturday by the Institute for the Study of War (ISW) went further. “Ukrainian forces have defeated the initial Russian campaign of this war,” it said. The conflict, it said, has now reached “a stalemate.”

Events on the battlefield could yet tilt in a different direction: for example, if the Russians succeed in capturing the besieged and desperate city of Mariupol, freeing up their forces to bolster their offensive elsewhere.

But in a widely shared March 14 article, a retired U.S. general and a European military academic argue that the Russian force is close to reaching what military strategists call the “culminating point” of its offensive, meaning that it will have reached the limits of its capacity to wage the war it set out to prosecute.