July 20 (UPI) — The average price of a gallon of regular grade gasoline in the United States has again reached $4 on Monday with renewed fighting in Iran.

AAA reported a 13-cent hike in the average gas price over the past week, bringing an end to declining prices. The latest surge comes on the back of the peace deal between the United States and Iran falling apart with both sides reigniting attacks.

The lowest gas prices in the United States on Monday can be found in Indiana, where a gallon of regular gasoline is $3.35. California has the highest average price per gallon at $5.49 and Washington and Hawaii are above $5 per gallon.

The average price of a gallon of gas was $2.98 before the United States and Israel launched strikes on Iran on Feb.28. Prices climbed quickly after that due to Iran effectively closing the Strait of Hormuz, a critical chokepoint in the Middle East oil trade. The average gas price in the United States topped $4.50 in May, marking a four-year high.

Brent crude oil, the international benchmark, surpassed $90 per barrel on Monday for the first time since early June. The price of Brent crude oil has climbed by 16% in the past week.

The price of a barrel of West Texas Intermediate crude oil has increased by $12 in July, hitting $82 per barrel.

Aggressions between the United States and Iran have brought the return of the U.S. naval blockade on the Strait of Hormuz. U.S. forces are again targeting any ships using Iranian ports.

U.S. economic data showed improvement beginning in June as talks of a peace agreement heated up. The White House welcomed a report from the U.S. Bureau of Labor Statistics last week that showed consumer prices falling in June.

“Prices are coming way down, and we’re doing a great job,” President Donald Trump told reporters last week. “And remember that for the midterms.”

The decline in consumer prices was largely attributed to falling gas and energy prices. Those prices were also the catalyst for prices surging over the past five months.