Two serious maritime incidents near the Strait of Hormuz heightened tensions in the Middle East after a ship anchored near the United Arab Emirates was reportedly seized and taken toward Iran, while another cargo vessel near Oman sank following an attack.

Officials have not confirmed who was responsible, though Iranian leaders recently reiterated claims of control over the strategic waterway and defended the seizure of oil tankers tied to the U.S.

The Strait of Hormuz remains a critical global shipping route through which a large share of the world’s oil supply passes, making the instability especially significant for global fuel markets.

The incidents come amid rising confrontation between the U.S. and Iran, including recent clashes in which U.S. forces disabled Iranian oil tankers accused of violating a blockade, the AP has reported.

During talks in Beijing, President Donald Trump and Chinese President Xi Jinping reportedly agreed that the Strait of Hormuz must remain open.