Donald Trump declared the Strait of Hormuz “permanently open” on Wednesday, following talks with his Chinese counterpart as pressure mounts on the US to end the war with Iran and restore global shipping.

The apparent climbdown came just hours after Trump said he was employing US forces to impose a blockade of Iranian ports in the region, a move the military said had completely halted trade going in and out of the country by sea.

Trump vowed to reopen the strait “for China” in an unusual concession to a trade rival. He promised “this situation will never happen again” and added that the Chinese leader would “give me a big, fat hug when I get there in a few weeks”.

Despite Trump’s social media post, the vital waterway remained restricted on Wednesday. A senior administration official told The Independent: “The blockade is fully in effect and working. As CENTCOM reported yesterday, no ships have made it past the blockade, which impacts vessels traveling to and from Iranian ports.

“The President has been clear that he wants the Strait to be open to facilitate the free flow of energy, and countries are also welcome to purchase oil from the United States of America.”

As Trump’s post prompted cautious signs of optimism, a Pakistani delegation headed for Iran to plan a second round of peace talks between Washington and Tehran, which could take place next week.

The US appeared to be hedging its bets with preparations to deploy 6,000 troops to the region on the aircraft carrier USS George H.W. Bush and several warships escorting it, according to the Washington Post. Another 4,200 were expected to arrive around the end of the month, joining some 50,000 personnel already in the area.

Addressing the growing military presence, White House press secretary Karoline Leavitt said Trump “has wisely kept all options on the table in the event that the Iranians will not forgo their nuclear ambitions and make a deal that is acceptable to the United States”.

The US military said meanwhile that nine vessels had complied with US forces directing them to turn around and head back towards Iran during the blockade of ports.

Even as the US military imposed its restrictions, Iran’s semi-official Mehr news agency reported that Tehran would switch to alternative ports, bypassing the US intervention.

Mediators are still trying to convene the second round of talks between Washington and Tehran to avert the reopening of hostilities, with a fragile two-week ceasefire set to expire next week.

Officials from Pakistan, Iran and several Gulf states said negotiating teams from the US and Iran could return to Islamabad later this week in an effort to save the lapsing truce agreement. Delegations are understood to have agreed to meet but are yet to settle on a date and time.

Trump was nonetheless optimistic about the state of negotiations, telling ABC News that he did not think it would be necessary to extend the ceasefire.

He told the world to brace for an “amazing two days”, assessing the war to be “close to over” in comments to Fox Business Network.

As Trump reached out to China, he continued his attacks on the Nato military alliance, writing on social media that “Nato wasn’t there for us, and they won’t be there for us in future”.

The remarks came hours after the Wall Street Journal reported that Europe was planning a “European Nato” without US involvement, incase Trump does decide to withdraw from the bloc.

An increasingly isolated Trump also threatened to rip up an historic trade deal with Britain, describing the so-called special relationship as being in a “sad” state, amid clashes over the conflict in the Middle East.

Sir Keir Starmer insisted he “won’t yield” to pressure from Trump to join the war.

He told MPs: “My position on the Iran war has been clear from the start. We’re not going to get dragged into this war. It is not our war.

“A lot of pressure has been applied to me to take a different course, and that pressure included what happened last night. I’m not going to change my mind. I’m not going to yield.

“It is not in our national interest to join this war, and we will not do so. I know where I stand.”