The U.S. Central Command confirmed the blockade would be "enforced impartially against vessels of all nations entering or departing Iranian ports."

Oil prices are rising in early market trading after the U.S. said it would blockade Iranian ports beginning Monday

The price of oil plunged well below $100 last Wednesday after Washington and Tehran agreed to a conditional two-week ceasefire deal that includes the opening of the key Strait of Hormuz trade waterway.

West Texas Intermediate and Brent crude both climbed above $100 a barrel on Monday after a breakdown in talks between the U.S. and Iran over the weekend.

Oil prices resumed their climb and global markets mostly declined Monday as the U.S. military prepared to blockade traffic to and from Iranian ports and the Strait of Hormuz, where most shipping has been stalled by Iran since the start of the war.

The Reuters Iran Briefing newsletter keeps you informed with the latest developments and analysis of the Iran war. The blockade, experts say, is an act ​of war that requires an open-ended commitment of a significant ​number of warships.

Oil prices have resumed their climb and Asian markets mostly declined as the U.S. military prepared to blockade ships entering or leaving the Strait of Hormuz, where most shipping has been stalled by

Stock-market futures were down Sunday evening, suggesting investors were bracing for a sharp drop in major indexes after weekend talks between the U.S. and Iran failed to open the Strait of Hormuz and led President Donald Trump to announce a blockade of the crucial waterway.