Oil prices were hovering just under $100 a barrel on Wednesday, as supply disruptions in the Strait of Hormuz left investors on edge even after U.S. President Donald Trump indefinitely extended a ceasefire with Iran.

Brent oil futures, the global benchmark, rose by 0.6% to $99.07 a barrel, while U.S. West Texas Intermediate crude futures gained 0.6% to $90.25 a barrel by 05:29 ET (09:29 GMT). Both contracts swung between positive and negative territory earlier in the session.

Tanker shipping through the Strait of Hormuz, a vital waterway off of Iran’s southern coast through which roughly a fifth of the world’s oil traverses, remains all but closed. Shipping monitor U.K. Maritime Operations said a container ship in the strait was attacked on Wednesday, shortly after a boat belonging to Iran’s Islamic Revolutionary Guards Corps struck a vessel in the area.

Trump announces indefinite extension to Iran ceasefire
Trump on Tuesday said he would indefinitely extend the ceasefire with Iran, allowing the two countries to continue peace talks to end the war. Iran’s foreign ministry spokesperson acknowledged the ceasefire extension in comments carried by Iranian state television, the Associated Press reported.
The status of future U.S.-Iran peace talks remained uncertain, especially after both Tehran and Washington declined to send delegates for more negotiations in Pakistan this week.

The president later claimed that Iran was losing $500 million a day from the effective closure of the Strait of Hormuz, and that there could never be a deal with Iran without lifting the blockade against the country.

A focal point of the conflict, the strait supplies roughly 20% of the world’s oil consumption. Hits to shipping activity, after Iran effectively blocked the crossing, provided a major boost to oil prices following the onset of the conflict in late February, leaving prices well above pre-war levels.

U.S. inventories, supply measures in focus
Elsewhere, industry data released overnight showed U.S. oil inventories shrank much more than expected in the week to April 17.

American Petroleum Institute data showed weekly crude inventories shrank 4.4 million barrels, much more than expectations for a draw of 1 mb.

The print usually heralds a similar reading from official inventory data, which is due later on Wednesday.

A sustained draw in U.S. inventories comes amid growing concerns over supply disruptions and price increases stemming from the Iran war. The U.S. was also seen undertaking measures to offset this impact, including potential draws from the Strategic Petroleum Reserve.

Axios reported that Trump was considering extending a waiver allowing foreign-flagged cargo ships to move fuel between domestic U.S. ports. Trump had announced the 60-day waiver in mid-March with the goal of allowing more domestic oil distribution to offset the impact of higher oil prices from the Iran war.

U.S. gasoline prices have jumped some 40% since the onset of the Iran war.
Source: Investing.com