Oil prices sank Thursday morning after President Donald Trump de-escalated tensions between Washington and Tehran saying "killing in Iran is stopping."

Following Trump's remarks, continuous futures contracts for Brent crude retreated by about 4.2% to roughly $63.73 a barrel. Elsewhere, WTI is down by 4.2% to $59.27.

Crude prices had been on a tear over the course of the five trading days ending Wednesday, as the Trump administration considered military action against the Islamic Republic.

Earlier this week, Trump also said he would impose a 25% tariff on any country doing business with Iran in the wake of deadly anti-government protests.

For now, the geopolitical risk premium, which had been supporting oil prices, appears to have tapered off. "Donald Trump appears to have pulled back from the brink of military intervention," says Darren Natahan at Hargreaves Lansdown.

Oil stocks suffered a leg down on the news. Chevron fell by 0.7% and Exxon declined 1% in pre-market trading. Shell was down by 1.7% and BP dropped by 2%.

Morning forward, traders look set to re-focus their attention on market fundamentals. Crude inventories in the U.S. climbed more than analysts expected -- by 3.4 million barrels to 422.4 million barrels -- last week.

Elsewhere, Venezuela's oil is set to return to markets, with the U.S. completing its first sale of Venezuelan oil on Wednesday. That should nudge near-term prices down. Still, oil traders should prepare for more volatility.