The US Central Command (Centcom) has said it will attack five Iranian oil tankers in response to Tehran targeting a US warship twice in the past two days.

Centcom said four Iranian oil tankers affiliated with the Iranian Revolutionary Guard Corps (IRGC) in the Gulf of Oman and another ship near the main oil terminal Kharg Island off Iran’s Gulf coast were targeted.

The BBC writes that Tehran responded by firing missiles at a US base in Jordan. However, Jordan said its air defenses shot down 18 of the 20 missiles launched by Iran.

The two countries have been engaged in a series of tit-for-tat attacks over the past week. The tensions have been simmering since the US and Israel launched their attacks on Iran on February 28, more than six months ago.

Meanwhile, oil prices rose in early trading in Asia. Brent crude rose 1.5 percent to $99.41 a barrel. U.S. crude rose 1.6 percent to $94.55.

A Jordanian military spokesman said two missiles fired from Iran into Jordan fell in uninhabited areas.

Iran has warned of further retaliation. It has urged crews of U.S.-flagged tankers near the ports of Kuwait and Bahrain to “stay anchored or in port—leave the ship immediately, as they will be targeted.”

The latest tensions came after Iran fired a ballistic missile at a U.S. warship, the BBC reported.

The missiles were “successfully evaded,” Centcom said, adding that no U.S. troops were injured in the attacks.

In response, the United States said the five Iranian oil tankers it attacked were “part of a multi-billion dollar shadowy network that funds the IRGC and its regional allies.”

The Iranian tanker hit in the latest US strike was near Kharg Island, home to Iran’s main oil export terminal.

About 90 percent of the country’s crude passes through the island, which is brought there by pipeline from the mainland.

Widespread regional instability has further pressured oil prices.

Meanwhile, Iran-backed Houthis in Yemen attacked energy facilities and civilian infrastructure in Saudi Arabia on Tuesday, wounding 73 people, Saudi authorities said.

Saudi Arabia’s military and energy ministry said drone and missile strikes set oil facilities and infrastructure on fire, temporarily halting operations.

Asked by reporters about the latest US-Iranian retaliation, US Secretary of State Marco Rubio said the situation was “pretty straightforward”.

“Iran continues to try to attack US naval vessels,” he said during a visit to Colombia.

“And every time they do or try to do that, they lose tankers. And I think you’ll see that again today.”

Hours before the US launched its attack on Tuesday, the Iranian navy claimed to have captured an unmanned US submarine in the Strait of Hormuz.

“The US-operated underwater drone was downed more than a day ago,” said US Navy Captain Tim Hawkins, a spokesman for CENTCOM.

He said the drone was being used to support ongoing operations in territorial waters.

He said the malfunctioning drone was “an older model, it did not collect any sensitive information and it did not have any classified sonar or radar equipment.”

He also said US operations in territorial waters were continuing.