NEW YORK (AP) — Oil prices rose in early market trading on Sunday after the U.S. said it would blockade Iranian ports beginning Monday.

The price of U.S. crude oil rose 8% to $104.24 a barrel and Brent crude oil, the international standard, rose 7% to $102.29.

Brent crude has swung dramatically during the Iran war, rising from roughly $70 per barrel before the war in late February to more than $119 at times. On Friday, ahead of the peace talks, Brent for June delivery fell 0.8% to $95.20 per barrel.

Iran has been effectively controlling the Strait of Hormuz, a key waterway for global oil shipping.

U.S. Central Command said the blockade would be “enforced impartially against vessels of all nations” entering or departing Iranian ports and coastal areas.

It said it would still allow ships traveling between non-Iranian ports to transit the Strait of Hormuz.

Around a fifth of the world’s traded oil typically flows through the Strait of Hormuz every day. Saudi Arabia, Iraq, the United Arab Emirates, Kuwait, and Iran are all major exporters.

Traffic in the Strait has been limited even in the days since the ceasefire. Marine trackers say over 40 commercial ships have crossed since the start of the ceasefire.