Oil prices gained more than $2 a barrel after having dropped sharply the day before. WASHINGTON — World shares declined Thursday following more of what the U.S. military said were defensive strikes against Iran. Oil prices gained more than $2 a barrel after having dropped sharply the day before. In early European trading, Germany’s DAX was nearly unchanged at 25,175.63 and the CAC 40 in Paris lost 0.4% to 8,172.84. Britain’s FTSE 100 slumped 0.9% to 10,416.62. This story continues below. The futures for the S&P 500 and the Dow Jones Industrial Average edged 0.1% lower.…