(CNBC) The Trump administration announced on Monday that it will no longer grant sanctions waivers to a handful of Iran’s oil customers, accelerating its mission of driving the Islamic Republic’s exports to zero.

The move threatens to wipe roughly 1 million barrels per day off the market at a time when analyst say oil supply is already tightening. Crude futures spiked to nearly six month highs on news of the move, which was first reported Sunday by the Washington Post.

The White House confirmed the reports ahead of a press conference with Secretary of State Mike Pompeo at 8:45 am ET.

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