An Iranian crude oil carrier identified as M/T Riesco sinks after being struck. [Photo Credit: Reuters]

Iran’s Revolutionary Guard said it ​fired ballistic missiles at a base in Jordan used by the U.S. military and attacked 10 ships on Wednesday, after the U.S. said it had destroyed ‌five Iranian oil tankers, in a sharp escalation of the six-month-old war.

Increased attacks by both the U.S. and Iran have shattered a month of relative calm, hitting military, shipping and energy assets, sending oil prices surging and drawing in regional allies in recent days.

The Americans said they destroyed five Iranian oil tankers on Tuesday. The U.S. military’s Central Command posted video of the strikes, which it called a response to Iran’s Islamic Revolutionary Guard Corps (IRGC) targeting ​a U.S. Navy warship twice with ballistic missiles over the previous two days. No Americans were harmed, the U.S. said.

Iran then carried out a ballistic missile attack on a base used by U.S. forces near Al Azraq in Jordan, according to an IRGC statement on state ​media.

Although Iran said its missiles inflicted heavy damage, Jordan said its air defences intercepted 18 of the 20 Iranian missiles, with two falling in unpopulated areas, and that there were no casualties. A ​U.S. official said Iran’s strikes in Jordan were ineffective and all American troops were accounted for.

The IRGC said on Wednesday it also attacked 10 ships, including two U.S. vessels and eight oil tankers, attempting to cross a “prohibited and unsafe” area of the Strait of Hormuz, a vital energy conduit largely choked off by Iranian attacks.

Iran has targeted U.S. assets and allies in the region throughout the war, including in Jordan several times, killing at least ​two U.S. military personnel during one strike in July.

Iran has also threatened oil tankers in Kuwaiti and Bahraini ports, according to a statement carried by state media. A maritime security source ​reported a liquefied natural gas tanker was damaged in the Emirati port of Khor Fakkan, though it was unclear who was responsible.

Oil prices extended gains in early trade on Wednesday with Brent crude nearing $100 a barrel ‌on market ⁠concerns over the disruption of oil tanker traffic in the Strait of Hormuz. Recent attacks by Yemen’s Iran-aligned Houthis on top energy producer Saudi Arabia have added to supply concerns.