Ukrainian servicemen of the 148th artillery brigade load ammunition into a M777 howitzer before firing towards Russian positions at the frontline in Zaporizhzhia region, Ukraine, on Thursday. (AP Photo/Evgeniy Maloletka)

DNIPROPETROVSK REGION, Ukraine (AP) — Ukrainian soldiers on the battlefield expressed little hope for a diplomatic solution to the war, as U.S. President Donald Trump’s deadline arrived Friday for the Kremlin to make peace and he eyed a possible summit meeting with Russian President Vladimir Putin to discuss Moscow’s invasion.

Exasperated that Putin did not heed his calls to stop bombing Ukrainian cities, Trump almost two weeks ago moved up his ultimatum to impose additional sanctions on Russia and introduce secondary tariffs targeting countries that buy Russian oil if the Kremlin did not move toward a settlement.

It was unclear what steps Trump intended to take. When asked Thursday whether his deadline would hold, Trump said of Putin: “It’s going to be up to him. We’re going to see what he has to say. It’s going to be up to him. Very disappointed.”

Trump’s efforts to pressure Putin into stopping the fighting have so far delivered no progress. Russia’s bigger army is slowly advancing deeper into Ukraine at great cost in troops and armor while it relentlessly bombards Ukrainian cities. Russia and Ukraine are far apart on their terms for peace.

Ukrainian forces are locked in intense battles along the 620-mile front line that snakes from northeast to southeast Ukraine. The Pokrovsk area of the eastern Donetsk region is taking the brunt of punishment as Russia seeks to break out into the neighboring Dnipropetrovsk region. Ukraine has significant manpower shortages.

Intense fighting is also taking place in Ukraine’s northern Sumy border region, where Ukrainian forces are engaging Russian soldiers to prevent reinforcements being sent from there to Donetsk.

In the Pokrovsk area of Donetsk, a commander said he believes Moscow isn’t interested in peace.

“It is impossible to negotiate with them. The only option is to defeat them,” Buda, a commander of a drone unit in the Spartan Brigade, told The Associated Press. He used only his call sign, in keeping with the rules of the Ukrainian military.

“I would like them to agree and for all this to stop, but Russia will not agree to that. It does not want to negotiate. So the only option is to defeat them,” he said.

In the southern Zaporizhzhia region, a howitzer commander using the call sign Warsaw, said troops are determined to thwart Russia’s invasion.

“We are on our land, we have no way out,” he said. “So we stand our ground, we have no choice.”

The Kremlin said Friday that Putin had a phone call with Chinese leader Xi Jinping, during which the Russian leader informed Xi about the results of his meeting earlier this week with Trump envoy Steve Witkoff. Kremlin officials said Xi “expressed support for the settlement of the Ukrainian crisis on a long-term basis.”

Putin is due to visit China next month. China, along with North Korea and Iran, have provided military support for Russia’s war effort, the U.S. says.

Trump said Thursday that he would meet with Putin even if the Russian leader will not meet with his Ukrainian counterpart Volodymyr Zelenskyy. That stoked fears in Europe that Ukraine could be sidelined in efforts to stop the continent’s biggest conflict since World War II.