Gas prices in the United States, above $4 per gallon, could continue to rise after Iran reportedly closed the Strait of Hormuz, a day after President Donald Trump announced a two-week ceasefire.

Iran closed the vital trade route in response to heavy Israeli bombardments on Lebanon, Iran’s semi-official Fars News Agency reported. However, White House Press Secretary Karoline Leavitt said those claims were untrue and the route had been reopened.

A key component of the ceasefire is for the strait to remain open while negotiations take place over the next two weeks. If the strait is now closed, as Iranian media reported, it's unclear what will happen now.

About 20% of the world’s oil passes through the strait, which was effectively shut down for weeks after the United States and Israel attacked Iran on Feb. 28.

Its closure sparked “the largest supply disruption in the history of the global oil market,” according to the International Energy Agency.