WASHINGTON/DUBAI/ISLAMABAD >> President Donald Trump said today he would indefinitely extend the ceasefire with Iran, hours before it was set to expire, to allow the two countries to continue peace talks to end a war that has killed thousands of people and shaken the global economy.

Backing down from new threats of violence earlier in the day, Trump said in a statement he had agreed to a request by Pakistan, which has mediated peace talks in the seven-week-old war, “to hold our Attack on the Country of Iran until such time as their leaders and representatives can come up with a unified proposal.”

Trump’s announcement appeared to be unilateral, and it was not immediately clear whether Iran or the U.S. ally, Israel, would agree to extend the ceasefire, which began two weeks ago. Trump also said he would continue the U.S. Navy’s blockade of Iran’s ports and shore, which Iran’s leaders have called an act of war.

There was no immediate comment from Iran’s most senior leaders, but Tasnim News Agency, affiliated with Iran’s Revolutionary Guards, said Iran had not asked for a ceasefire extension and repeated threats to break the U.S. blockade by force. An adviser to Iran’s lead negotiator, the speaker of parliament, Mohammad Baqer Qalibaf, said Trump’s announcement carried little weight.

“Trump’s ceasefire extension is certainly a ploy to buy time for a surprise strike,” Mahdi Mohammadi, the parliament speaker’s adviser, said in a statement on social media, calling the U.S. blockade an ongoing military aggression. “The time for Iran to take the initiative has come.”

Trump said he would extend the ceasefire until Iran’s “proposal is submitted, and discussions are concluded, one way or the other.”

It was the latest instance of Trump backing down at the 11th hour from his repeated threats to bomb every power plant in Iran. United Nations Secretary General António Guterres and others have condemned the threats, noting international humanitarian law forbids attacks targeting civilians and civilian infrastructure.

Trump, who with Israel launched the war on Iran on February 28, said he decided to extend the ceasefire because “the Government of Iran is seriously fractured, not unexpectedly so,” a reference to U.S.-Israeli assassinations of some of the country’s leaders, including the late Supreme Leader Ayatollah Ali Khamenei, who has been succeeded by his son.

The U.S. blockade became a sticking point as the two countries wavered this week on whether to send negotiators to a second round of peace talks in Islamabad, the Pakistani capital.

The ceasefire extension came only a few hours after Trump had said he was not inclined to continue the temporary truce and the U.S. military was “raring to go.” He told CNBC in an interview that the U.S. was in a strong negotiating position and would end up with what he called “a great deal.”

Pakistani Prime Minister Shehbaz Sharif thanked Trump in a statement on social media for “graciously accepting our request to extend the ceasefire to allow ongoing diplomatic efforts to take their course.”

“I sincerely hope that both sides will continue to observe the ceasefire and be able to conclude a comprehensive ‘Peace Deal’ during the second round of talks scheduled at Islamabad for a permanent end to the conflict,” Sharif wrote.

It was not clear when, or if, that second round of talks would be scheduled.