Iran's parliament speaker Mohammad Bagher Ghalibaf warned Sunday of a faster, heavier, and more painful response to US attacks, saying Americans must understand that the rules of the game have changed. The warning comes nearly a week into renewed fighting between the two countries and a day after the United States said it struck Iranian oil tankers in response to Tehran attacking American warships in the region.

The fighting resumed last Sunday after a 60-day ceasefire formally expired last month. Throughout the week, the US launched multiple strikes on Iranian targets while Iran retaliated against US targets in the United Arab Emirates, Bahrain, Kuwait and Jordan. Iranian state media reported Sunday that the country's Navy attacked an American remote-controlled vessel attempting to enter the Strait of Hormuz, a claim the US military denied. US Defence Secretary Pete Hegseth wrote on social media Saturday that if Iran shoots at US ships, the US will destroy and sink Iranian oil tankers.

The Strait of Hormuz, crucial to the global oil and gas industry, has been effectively closed since the six-month-long war began in February and has become a major source of leverage for Iran. Tehran has insisted it will not relinquish control over the waterway, while President Donald Trump has declared the strait open and deployed the US military to help ships navigate the southern route.

The conflict has driven up gas prices globally. The average price for one gallon of diesel in the US hit $5.85 on Friday, compared to $3.71 a year ago. US Energy Secretary Chris Wright said Sunday that an average of 9 million barrels of oil per day are now passing through the strait. Wright told ABC that with oil also moving through regional pipelines, flows have reached two-thirds or more of pre-conflict levels, and he expects gas prices to decline as summer demand wanes after Labor Day.