Explainer-How Western sanctions will target Russia

A view shows the Russian embassy building in Kyiv, Ukraine February 23, 2022. REUTERS/Valentyn Ogirenko

(Reuters) - The United States and its allies have vowed to hit Russia with harsh sanctions after Russian forces invaded Ukraine on Thursday in a massed assault by land, sea and air - the biggest by one state against another in Europe since World War Two.

Western capitals introduced an initial round of sanctions after Russian President Vladimir Putin recognised two breakaway regions in eastern Ukraine on Monday.