Stock prices plummeted worldwide on Tuesday after Russian President Vladimir Putin ordered his troops to enter two separatist regions in eastern Ukraine, increasing the likelihood of a long-anticipated invasion. The "Nikkei 225" index in Tokyo fell by 2.2%, while the "Hang Seng" index in Hong Kong dropped by 3.2% in early trading, according to the Associated Press. Oil prices surged, with U.S. crude rising by 2.8%. Futures for the "S&P 500" index decreased by 1.7%, while the "Dow Jones" industrial index futures fell by 1.5%. In Europe, stocks declined on Monday as investors awaited developments in the Ukraine crisis. The German "DAX" index lost 2.1%. In Paris, the "CAC 40" index fell by 2%, and the British "FTSE 100" index dropped by 0.3%. The Russian "MOEX" index fell by about 11%. The ruble declined by 3.2% against the dollar. Western powers fear that Russia could use the skirmishes in eastern Ukraine as a pretext for an invasion of the country, which has resisted Moscow’s attempts to draw it back into its sphere of influence.