CNBC newsletter warns of oil supply shock risks from Iran, Hormuz and the Red Sea

U.S. oil just topped $90 a barrel and Brent crude passed $100 a barrel.

A number of new factors could mean this crude comeback has legs.

One question the piece raises is what would happen if all Iranian oil suddenly went offline. The article says Iran is still selling some oil on global markets, and it points to possible disruption at Kharg Island or a shutdown by the National Iran Oil Co. employees as scenarios that could hit output.

Oil expert Eric Nuttall of Ninepoint Partners says the world cannot afford to lose another 2.6 million barrels per day of Iranian production, given already tight Middle East supply, low inventories, a depleted U.S. Strategic Petroleum Reserve and tight refined product stocks. Kevin Book of Clearview Energy Partners says the key factor would be how long Iranian oil stayed offline, but he sees at least a $5-per-barrel increase. Bob McNally of Rapidan Energy Group says if actual production closed, refineries would shut down, refined products would run out, and transportation would grind to a halt.

The article also turns to the Bab el-Mandeb Strait, the narrow waterway between Yemen and Africa that is critical for oil and product flows. It says the risk there is real and may help explain why Brent crude is nearing $100 a barrel. Tobin Marcus of Wolfe Research says the market expects de-escalation, but he warns against underestimating supply disruption risks around the Red Sea.

The piece says attacks linked to the Houthis have reduced crude tanker traffic through the southern route and that insurance demand has weakened because ship traffic has slowed. It also says Saudi Arabia is moving more oil through its East-West pipeline to Yanbu, which means Houthi attacks could threaten about 4.5 million barrels of oil per day.

The newsletter argues that stocks can keep rising even when oil and gasoline rise, citing stronger fuel efficiency, more remote work and spending supported by A.I.-related investment. It says travel demand remains strong despite higher fuel costs.

On Wall Street, Goldman Sachs says Brent crude could rise above $120 per barrel in the fourth quarter if Hormuz remains disrupted. Goldman also says recent inventory draws have made the market more vulnerable, although weaker Chinese crude imports could cap prices relative to earlier estimates.

The article says the U.S. continues selling oil from the Strategic Petroleum Reserve and that concerns are growing about reaching "tank bottoms," where further withdrawals become difficult.

It also highlights more than $60 billion in planned American investment in Iraq. The article names Chevron, ConocoPhillips, Shell, BP, Halliburton, JPMorgan Chase, PepsiCo, Abbott and Thermo Fisher Scientific among the companies involved, and says President Donald Trump and Iraq's prime minister spoke about the deal from the White House.

Chevron is said to be in talks to rebuild a pipeline from Kirkuk to the Syrian coast and to invest in Iraqi oil fields. The article says UBS has a $220 price target on Chevron. ConocoPhillips is described as planning to invest alongside BP by buying a 42% stake in an oilfield, while Evercore ISI says the move could raise questions about the company's resource and free-cash-flow strategy.

Excelerate Energy is also involved in the Iraq investments. Goldman Sachs initiated coverage with a buy rating and a $49 target, saying the company should benefit from its regasification and storage business and its vertical integration opportunities.

The article says higher oil prices have also lifted oil and gas stocks, with Marathon Petroleum up 25% in July and hitting record highs.

It closes by noting that Ukraine continues striking Russian energy assets, with about 2.7 million barrels per day of Russian refining offline. The piece says this may be pushing additional oil onto export markets and holding crude prices down from even higher levels.