In short:
The entry of the Houthi rebels into the war between the US and Iran threatens another vital shipping route through the region, as the entire region remains on high alert.
Oil prices have once against surpassed $US100 a barrel amid concerns about what a Houthi blockade could mean for oil shipments in the Red Sea.
US President Donald Trump is threatening to hold Iran responsible for the Houthi's actions.
Oil prices have tipped back over $US100 a barrel ($143) for the first time in two months, as the US president vows to hold Iran responsible for any attacks by the Houthi rebels in Yemen on Saudi oil tankers.
The Houthis announced a blockade of long-time enemies Saudi Arabia earlier in the week, following a flare up in their more then decade long war.
It has led to disruptions to shipping in the Red Sea, and specifically through the Bab el-Mandeb Strait between Yemen and the Horn of Africa.
In a post on his Truth Social platform, US President Donald Trump said the Houthis had opened fire on two Saudi tankers on Wednesday.
"Please let this TRUTH serve to represent that if they do this again, the U.S. will hold Iran responsible, in that the Houthis are a Surrogate and/or Proxy of Iran, and major military punishment will be inflicted upon Iran and, of course, the Houthis, themselves, who I am very disappointed with in that they have, until now, acted very professionally and smart," he said.
Iranian state media later reported sounds of explosions on Qeshm Island, located in the Strait of Hormuz.
The president also cited previous US strikes on the Houthis in his post.
"A year ago the United States of America attacked, very powerfully, the Houthis, for their interference with commerce and trade, by shooting at ships," he posted.
The Saudis had been using the Bab el-Mandeb, which translates to "Gate of Tears" to ship oil otherwise blocked from global markets by Iran's closure of the Strait of Hormuz, on the other side of the Arabian Peninsula.
The oil-rich nation pumped millions of barrels through its East-West pipeline, taking supplies from its large east coast production hubs to its Yanbu port on the west coast.
Both the pipeline and the Yanbu facility were attacked by Iran at the height of the US and Israel's war against Tehran.
Brent Crude rose more than 6 per cent on Thursday, crashing through the $US100 a barrel price, off the back of the blockade concerns.
Earlier, the US Secretary of State Marco Rubio told reporters at the ASEAN summit in the Philippines he believed the Houthis had been "suckered into" the war by their Iranian backers.
The Reuters news agency has reported the Saudi state-owned oil company Aramco has begun offering customers more oil shipments from ports in Egypt, as it seeks to avoid the Houthi blockade.
Both sides launch attacks
The development comes as the Middle East region remains on high alert, with daily fire between the US and Iran across the Persian Gulf and beyond.
The US has continued to attack Iranian infrastructure along the gulf coast, following Mr Trump's warning that bridges and power stations would be targeted if the Iranians attacked ships in the Strait of Hormuz.
In response, Iran continued to launch missiles and drones at claimed US military targets in the region, including sites in Jordan.
The Jordanian army said Iran fired four missiles and six drones at the kingdom, triggering the country's air defence systems.
It's now more than a fortnight since Donald Trump declared the interim deal he signed with Iran to immediately end fighting, and begin negotiations on the future of its nuclear program and the management of the Strait of Hormuz, was over.
The war with Iran is now almost five months old.
To this point, Israel has not returned to the fighting, however authorities have been monitoring the deteriorating situation closely.
Local media has reported some municipalities have reopened public bomb shelters ahead of any strike by the Iranians on Israel, although the Israeli military's Home Front Command has not issued any formal directive at this point.
Some hospitals were reportedly also preparing their fortified underground wards.
