The Mechanism That Worked, Then Didn't

On June 25, the Commerce Department released inflation data that contained a sentence worth reading again now. The report noted that a "preliminary peace deal between the U.S. and Iran to reopen shipping lanes subsequently pushed oil prices down from $113 to under $70 per barrel, which may provide a path for the Fed to maintain current rates if energy costs continue to fall." ^[1] The ceasefire was not merely a pause in hostilities. It was an inflation instrument, and the data shows exactly how it worked. During the three weeks the truce held, traffic through the Strait of Hormuz rebounded 54% week over week, reaching 24 vessels per day. ^[2] Brent crude fell from $113 to $73. Headline PCE dropped from 4.2% in May to 3.5% in June. Each link in the chain was measured and real. But the Fed's own analysis, published July 19, reveals what the ceasefire was not doing. While headline inflation fell, core PCE remained stuck at 3.36% and rising. ^[3] The ease was suppressing only the energy leg of inflation. Beneath it, two other drivers held firm: AI infrastructure spending and tariffs, which the Fed's July 10 report identified as structural forces pushing core inflation higher even as oil prices dropped. ^[4] On July 9, the mechanism broke. Iran attacked three commercial ships in the Strait of Hormuz. Trump declared the memorandum of understanding "no longer valid" and engagement "futile." ^[5] The diplomatic instrument that had created the ease no longer exists. The reversal was mechanical and immediate. Hormuz traffic collapsed to four ships per day by July 19, with zero LNG tankers since July 16. ^[6] Brent crude surged back above $90 on July 20, erasing the entire ceasefire-era price decline. ^[7] The IMF lowered its 2026 global growth forecast to 3.0% the day the ceasefire died, and Hormuz oil flows dropped from 20 million to 14 million barrels per day. ^[5] Then a second, independent supply shock landed on top. Ukrainian attacks have eliminated roughly 25% of Russia's refining capacity, forcing Russia to ban diesel exports and import gasoline from India. Diesel futures climbed 12% to $154.71 per barrel, and European premiums hit a 15-year high. ^[8] GasBuddy's Patrick De Haan put the shift plainly.

Average gasoline and diesel prices rose in nearly every state for the second straight week, with the national average price of gasoline likely to reach $4 per gallon within the next 48 hours and diesel already back above $5 per gallon nationally. — Patrick De Haan

The national average gas price reached $3.95 on July 20 and was expected to hit $4 within 48 hours, with diesel already above $5. ^[9] Even if the Iran war ended tomorrow, the refinery damage persists. The price floor is now reinforced from a direction a ceasefire could not have fixed. The Fed's posture tracked this sequence exactly. On July 8, the last full day of the ceasefire, the central bank was divided and holding rates at 3.50–3.75%, with Governor Warsh calling AI "a significant disinflationary force" and projecting the 2% target by 2028. ^[10] By July 15, six days after the collapse, the tone had flipped. Governor Cook signaled readiness to raise rates, saying inflation remained too high. Governor Waller invoked the 2021 mistake directly. ^[11] By July 20, traders were pricing an 82% probability of a December rate hike, with Cleveland Fed President Hammack indicating rates "may need to rise to combat persistent inflation, which could be stoked by rising energy costs." ^[12] What makes this sequence different from the March-to-May spike is that the buffers are gone. The Strategic Petroleum Reserve was drained in May, when the administration also eased sanctions on Russia and Venezuela to increase supply. ^[13] Those measures are spent, and no new ones have been created. The Gulf states are building bypass pipelines, but the UAE's will not complete until 2027, Iraq's Basra-Ceyhan line remains a feasibility study, and Iran has threatened to close the Bab el-Mandeb Strait, the alternate chokepoint the Saudi Red Sea route passes through. ^[14] The Saudi East-West pipeline handles roughly 5 million barrels per day for export, but the Hormuz blockade shut in as much as 12 million barrels per day before the June ceasefire. ^[15] Even existing bypass capacity covers less than half the lost volume, and the expansion that might close the gap will take years. Occidental Petroleum's Q2 earnings tell the story in a single number. The company's average realized oil price was $96.78 per barrel, up 38.4% from Q1's $69.91. ^[16] The sub-$73 pricing of the ceasefire weeks was the anomaly. $90-plus is the floor, and the one tool that briefly pushed against it has been broken by the same war it was meant to pause.