Brent crude prices fell almost $1 a barrel on Tuesday, with an Iranian delegation in Beijing this week to push for more oil sales. Oil markets were also pressured as Goldman Sachs (GS.N) said prices needed to remain low for months to achieve a slowdown in U.S. output growth. China is Iran’s largest trade partner and also its largest oil client, having bought roughly half of Iran’s total crude exports since 2012, when sanctions against Iran were tightened.