Oil prices jumped 5% on Monday after Donald Trump reinstated the US blockade of Iranian shipping in the Gulf, adding a 20% toll on other countries' cargo for the privilege of passing through the Strait of Hormuz - because nothing says 'guardian' like a surcharge.

Brent crude hit $79.37 a barrel, climbing from $72.48 before the US-Israeli strikes on Tehran in late February. The price had peaked at $120 in April, so this is practically a bargain.

In a social media post, Trump declared the US would henceforth be known as 'THE GUARDIAN OF THE HORMUZ STRAIT,' effective immediately. The title comes with no cape, but presumably a bill.

The move rattled markets worldwide. Asian stocks took a beating, with South Korea's Kospi down 8% and Japan's Nikkei 225 and China's Shanghai Composite each falling 2%. Chipmakers were particularly singed: SK Hynix slumped 15%, while Samsung Electronics sank 10%.

US stocks also felt the heat, with the Nasdaq down 1% and the S&P 500 off 0.4%. Airline shares on both sides of the Atlantic took a nosedive.

The escalation follows US strikes on Iran Sunday evening, which Tehran promptly returned. US Central Command said the strikes aimed 'to continue degrading their ability to attack civilian mariners and commercial ships freely transiting the strait.' Because nothing says 'free transit' like a blockade and a toll.

The fragile US-Iranian truce signed last month is looking increasingly fragile. Goldman Sachs analysts noted that 'recent attacks highlight how uncertain Gulf exports remain,' which is analyst-speak for 'brace for higher gas prices.'

Data from Kpler shows only six vessels crossed the strait on Sunday - the fewest in five weeks. Tankers are already switching off transponders, because when you're smuggling oil, stealth is key.

Gold fell 1.4% to $4,083 an ounce, as higher oil prices stoked fears of interest rate hikes - because gold doesn't pay yield, but it does have a great sense of timing.

Oil prices later pared gains after OPEC lowered its 2026 global demand growth forecast to 780,000 barrels a day, down from 970,000 - the third consecutive downward revision. The International Energy Agency is even more pessimistic, expecting demand to decline by 1 million barrels a day. But hey, at least the Strait is guarded.