U.S. and global oil futures declined on Thursday as a hefty rise in last week’s U.S. supplies and uncertainty surrounding tariff disputes helped to weaken the outlook for crude demand, prompting prices to settle at their lowest levels of the year.

Oil prices fell more than 2% on Wednesday as a large build in U.S. crude and gasoline stockpiles signalled demand weakness while concern about a new China-U.S. trade war fuelled fears of softer economic growth.

Oil prices on the New York commodity exchange are dropping after China imposed tariffs on American goods, including oil and liquefied natural gas. Brokers report that investors are also worried about US sanctions on Iran.