WASHINGTON — An island one-third the size of Manhattan controls virtually all Iranian crude oil exports — and experts say its fate could be essential to President Trump’s endgame with Tehran . Kharg Island is located about 16 miles off the Iranian coast in the Persian Gulf, making it difficult to defend and easier to isolate — reportedly drawing the attention of administration planners. “Kharg Island handles roughly 90% of Iran’s crude oil exports. Take it out, and this means cutting off the