KRAMATORSK, Ukraine -- At one point during a grueling 110-day tour in the obliterated frontline Ukrainian city of Toretsk, Dmytro, a soldier with Ukraines 100th Separate Mechanized Brigade, listened in to the radio traffic among Russian soldiers.

We repeatedly heard commanders orders to the stormtroopers: Dont take anyone alive,he said in an interview last month in Kramatorsk, about an hours drive to the northwest. He spoke on condition only his first name be used. The fighting here was heavy, as you understand."

As Russias all-out invasion grinds into its fourth summer, Ukraines beleaguered and exhausted units, like the 100th Brigade, continue to be slowly ground down by a larger army, with more men, more weapons, more ammunition, and a Kremlin determined to force Kyiv capitulate.

Russia has ramped up the pace of operations on the battlefield in recent weeks. Whether that constitutes its anticipated summer offensive, or if that effort is still to come, is an open question.

Either way, Moscow is expected in the coming months to hit a gruesome milestone:1 million of its own troops killed or wounded. That is well in excess of all casualties suffered by Russia and the Soviet Union in all the conflicts since World War II combined.

The summer offensive is not yet under way, said Ivan Torres, a retired US Army major who is now senior Russian armed forces analyst for Rochan Consulting, a Polish research group.

The Russians are currently transitioning to the summer campaign season, consolidating recent gains, reconstituting their forces, and bringing up reserve forces and equipment, all while maintaining pressure and offensive momentum, he said.

What [the Russians] want by end of the summer offensive is to take all of Donetsk [region]. Theyve made slow incremental advances but with very, very high casualty rates, said Rajan Menon, director of the Grand Strategy Program at Defense Priorities, a Washington think tank.

Heres a snapshot of where things stand more than 40 months into Europes largest land war since 1945.

A small market in the village of Stets'kivka, near the front line, in the Sumy region, on June 12.

Sumy

The 1,100-kilometer front line where Ukraine has struggled to hold back Russian forces stretches roughly from the lower reaches of the Dnieper River near the southern city of Kherson to the northeast near the cities of Pokrovsk and Toretsk, then north to Chasiv Yar and Kupyansk near the Russian border region of Belgorod.

But 300 kilometers northwest of Kupyansk, Russian troops are bearing down on Sumy, a city with a prewar population of 255,000.

Sumy sits on a major highway that runs north to the Russian border and the Kursk region, which Ukraine invaded last August, embarrassing the Kremlin. In late April, Russian troops, bolstered by around 11,000 North Koreans, finally pushed the last Ukrainian units out of Kursk.

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In recent weeks, Russian commanders launched a focused, small-scale offensive from the north targeting Sumy. As of July 3, Russian forces were around 20 kilometers outside the city.

Russian officials have justified the push toward Sumy as an effort to create a deep buffer zone along the border. Asked about the offensive during a St. Petersburg investment conference in mid-June, President Vladimir Putin issued a thinly veiled threat to seize the city.

We dont have a goal to take Sumy. But in principle, I dont rule it out, he said.

Days later, on June 26, Ukraines top commander claimed that the Russian advance on Sumy had been stopped.

Based on the results of May and June, we can say that the wave of attempts at a summer offensive launched by the enemy from Russian territory has been choked off,General Oleksandr Syrskiy said.As of this week, the advance of Russian troops in the border area of the Sumy region has been stopped, and the line of combat contact has been stabilized.

Sumy is a supporting effort, though an important one, Torres said. It keeps significant Ukrainian forces tied down in a noncritical operational direction while allowing the Russians to gain control of an essential piece of terrain.