Ukraine thwarts Russian advances; fight rages for Mariupol

A car destroyed by shelling is seen in a street in Kharkiv, Ukraine, Tuesday, March 22, 2022. (AP Photo/Andrew Marienko)

Ukrainian serviceman has a rest on his position in Kharkiv, Ukraine, Tuesday, March 22, 2022. (AP Photo/Andrew Marienko)

People roam around a used-books street market in downtown Lviv, western Ukraine, Tuesday. The U.N. refugee agency says more than 3.5 million people have fled Ukraine since Russia's invasion, passing another milestone in an exodus that has led to Europe's worst refugee crisis since World War II. (AP Photo/Bernat Armangue)

A woman waits for a transport after fleeing the war from neighbouring Ukraine at a railway station in Przemysl, Poland, on Tuesday, March 22, 2022. (AP Photo/Sergei Grits)

Ukrainian President Volodymyr Zelenskyy appears on the television inside a bar in downtown Lviv, western Ukraine, Tuesday, March 22, 2022. Ukrainian forces fought off continuing Russian efforts to occupy Mariupol and claimed to have retaken a strategic suburb of Kyiv on Tuesday, mounting a defense so dogged that it is stoking fears Russia's Vladimir Putin will escalate the war to new heights. (AP Photo/Bernat Armangue)

An elderly woman walks pass concrete blocks topped with sandbags at a street in Odesa, southern Ukraine, on Tuesday. (AP Photo/Petros Giannakouris)

KYIV, Ukraine — Ukrainian forces battled continuing Russian efforts to occupy Mariupol and claimed to have retaken a strategic suburb of Kyiv on Tuesday, mounting a defense so dogged that it is stoking fears Russia’s Vladimir Putin will escalate the war to new heights.