US President Joe Biden was a few dozen kilometres from the Ukrainian border on Friday to speak to US troops protecting NATO’s eastern flank and to be briefed on Poland’s response to the influx of refugees fleeing Russian attacks. Biden also paid tribute to the “guts” shown by Ukrainians as the war grinds into its second month and the humanitarian crisis worsens. “The Ukrainian people have a lot of backbone. They have a lot of guts. And I’m sure you are observing it. And I don’t just mean the military … but also the average citizen,” he told a room of US service members in the small city of R…