KYIV, March 30 (Reuters) - Russia on Thursday charged an American correspondent for the Wall Street Journal with spying, in a case certain to escalate Moscow's diplomatic feud with Washington over the war in Ukraine and likely to further isolate Russia. The Institute for the Study of War think tank said Russian troops and Wagner mercenaries had captured territory in the south and southwest of the city over the past two days, and Wagner had occupied a metal plant in its north this week. Russia's invasion has destroyed Ukrainian cities and set millions of refugees to flight