President Biden traveled to this southeastern Polish city Friday to visit U.S. troops deployed along NATO’s eastern fringe as a bulwark against Russian incursion, and to laud Poland’s humanitarian role in welcoming more than 2 million Ukrainian refugees.

Biden, who met with members of the 82nd Airborne Division and Polish President Andrzej Duda, said he regretted that he could not cross the border into Ukraine, barely 60 miles away, to see the crisis firsthand.

But inside Ukraine, where Russia’s brutal onslaught continued, a senior aide to President Volodymyr Zelensky said officials were “very disappointed” in the outcome of the series of summits Wednesday among NATO and European Union leaders in Brussels that brought Biden to Europe.

“We expected more bravery. We expected some bold decisions,” Andriy Yermak, Zelensky’s chief of staff, told the Washington-based Atlantic Council via live video Friday.

U.S. and Ukrainian officials believe that the Russian operation has already failed in some respects, given strong Ukrainian resistance and heavy Russian losses, and Russia signaled Friday its aims might be narrowing. But Yermak’s remarks served as a reminder that Ukraine remains outmanned, outgunned and facing more destruction each day. The Pentagon said Friday Russia has begun to mobilize military reinforcements to possibly send into Ukraine.