A ship anchored off the United Arab Emirates (UAE) was seized and taken toward Iran and another — a cargo ship near Oman — sank after being attacked, authorities said on Thursday, as tensions escalated near the Strait of Hormuz.

It was not immediately clear who was behind these incidents, but they happened as a senior Iranian official reiterated his country’s claim of control over the waterway and another said it had a right to seize oil tankers connected to the US.

The turmoil in the strait has been a sticking point for weeks in talks between the US and Iran to end the conflict. Iran’s grip on the vital waterway has jolted the world economy and spiked fuel prices far beyond the Middle East.

The ongoing instability in the region came as US President Donald Trump met with Chinese President Xi Jinping (習近平) in Beijing. The White House said both sides had agreed that the Strait of Hormuz must remain open.

Just last week, tensions flared in the strait when US forces fired on and disabled Iranian oil tankers that they said were trying to breach its blockade of Iran’s ports.