Iran’s parliament voted on Sunday to support closing the Strait of Hormuz, a critical oil shipping route, following U.S. airstrikes on Iranian nuclear sites. 

About one-fifth of the world’s oil and gas shipments pass through the narrow waterway linking the Persian Gulf to the Gulf of Oman. A shutdown of this route could drive up fuel prices worldwide, impacting consumers everywhere, including in the U.S. 

Although Iranian state media claimed that the parliament approved a move to close the strait, the final authority to make that decision rests with Iran’s Supreme National Security Council.

On Sunday, U.S. Secretary of State Marco Rubio urged China to pressure Iran against closing the strait. 

“I encourage the Chinese government in Beijing to address this issue directly, as they rely heavily on the Strait of Hormuz for their oil supplies,” Rubio said in an interview on Fox News. China, Iran’s largest oil buyer, continues to maintain strong ties with the Islamic Republic.

Iran exported 1.84 million barrels of oil per day last month, mostly to China, according to shipping data from Kpler. “It would be a self-inflicted wound,” Kpler oil analyst Matt Smith told CNBC as he pointed out that Iran also relies on the strait for its own oil exports.

Rubio described a potential closure of the strait as a significant escalation that would warrant a response from the U.S. and other nations. 

Iran’s foreign minister said Sunday that the country “reserves all options to defend its sovereignty,” following U.S. airstrikes that deployed bunker-buster bombs, Tomahawk missiles, and more than 125 aircraft to hit three of Iran’s nuclear facilities.

While Iran has not yet launched a direct attack on U.S. forces, it responded Sunday morning by firing over 40 ballistic missiles at northern and central Israel, injuring at least 86 people.

The Chinese embassy in Washington did not immediately respond to requests for comment.