US stock markets dropped again on Friday, capping off a fourth week of market turbulence as investors worried about the US-Israel war on Iran and its widespread impact on global oil prices.

The Dow lost over 400 points on Friday, with the S&P 500 slipping 1.5% and the tech-heavy Nasdaq down 2%.

The biggest losses of the week were seen in the Russell 2000, which tracks the performance of small-cap companies. The Russell 2000 entered correction territory on Friday after dipping 2.7%, meaning the index fell more than 10% from its most recent high. The small cap index is the first of all the major indices to enter correction territory this year.

Since 28 February, the Dow, S&P 500 and Nasdaq indices have dropped about 7%, 5% and 4.5%, respectively – still far from correction territory, but dips have become a mainstay over the last few weeks.

Markets seem particularly attuned to skyrocketing oil prices, which affects everything from shipping trucks and commercial airlines to fertilizer for farming.

The price of Brent crude oil, the global benchmark, reached $107 a barrel by Friday afternoon, with prices typically hovering around $70 a barrel before the start of the conflict. US crude oil reached $98 a barrel, up from an average of $64 a barrel before March.

US gas prices at the pump are an average $3.88 a gallon, according to AAA, with averages surging past $5 in states such as California, Washington and Hawaii.

The strait of Hormuz, where a fifth of the world’s oil supply typically passes through, remains blocked in retaliation of the US-Israel strikes against Iran. Both sides of the conflict have also targeted key energy infrastructure in the Gulf states and Iran, which could take years to repair.

After Israel attacked Iran’s South Pars gasfield, Tehran struck Ras Laffan, the world’s largest liquified natural gas (LNG) facility in the world, earlier this week.

Donald Trump has spent much of the last week attacking US allies for refusing to help the US reopen the strait of Hormuz, calling Nato allies on Friday “cowards”.

“COWARDS, and we will REMEMBER!” the US president wrote on social media, telling reporters later on Friday that “you don’t do a ceasefire when you’re literally obliterating the other side”.

The Pentagon deployed about 2,200 marines to the Middle East on Friday, though the White House hasn’t specified what missions the deployment will assist.