Sources tell Al Jazeera that Pakistani mediators are hopeful about a breakthrough on Iran’s nuclear programme.

A high-level Pakistani delegation has travelled to Iran to hold talks focused on arranging a fresh round of negotiations between Iran and the United States, a week before their fragile truce is due to expire.

Pakistan Army Chief Asim Munir is heading the delegation that arrived in Tehran on Wednesday evening, according to Iranian state media. It said he came with a new message from the US and plans to coordinate a second round of US-Iran talks, after an initial round in Islamabad ended on Sunday without a deal to end the war.

Pakistan’s Interior Minister Mohsin Naqvi is also joining mediation efforts in Tehran, while Pakistan’s Prime Minister Shehbaz Sharif is in Saudi Arabia for the first stop in a four-day Gulf tour.

Pakistan’s diplomatic blitz comes as competing US and Iranian sea blockades strain tensions – and the global economy – but amid indications of progress towards a deal to end the war, which has killed 3,000 people in Iran and spiralled across the Middle East.

“The urgency is being driven by the ceasefire expiring on April 22, and Pakistani officials are hoping they can get that extended,” said Al Jazeera’s Kimberly Halkett from Islamabad. “Sharif will try and convince regional partners to also use their leverage to convince the US to participate in new talks with Iran and make sure there is no diplomatic line-crossing.”

Washington ‘feels good’ about potential deal

The latest mediation appears bolstered by optimistic comments from US President Donald Trump, who said the world should brace for an “amazing two days” as the war with Iran is close to over.

Trump also said his negotiators were likely to return to Pakistan, thanks largely to the “great job” Munir was doing to moderate the talks.

White House press secretary Karoline Leavitt later reiterated that additional talks with Iran would likely go forward in Islamabad. “We feel good about the prospects of a deal,” she told reporters on Wednesday.

Nevertheless, the US military said its naval blockade on all Iranian ports was still in effect, with US forces “present, vigilant and ready to ensure compliance”.

The blockade, which Iran’s military slammed as a violation of the ceasefire, turned nine ships away as of Wednesday, according to US Central Command.

The commander of Iran’s joint military command, Ali Abdollahi, threatened to halt trade in the region if the US did not lift its blockade. He also warned Iran would retaliate by blocking trade through the Red Sea along with the Gulf and Sea of Oman.

‘Detractors on all sides’

Mediators in the conflict are pushing for a compromise on three main sticking points – Iran’s nuclear programme, control of the Strait of Hormuz, and compensation for wartime damages.

Iran’s Foreign Minister spokesman Esmaeil Baghaei has said Iran is open to discussing the type and level of its uranium enrichment, but his country “based on its needs, must be able to continue enrichment”, according to Iranian state media.

Sources told Al Jazeera that Pakistani mediators are optimistic about a potential major breakthrough on the nuclear front, which is the reason for Munir’s rare diplomatic trip.

“It looks like there is some agreement in the making, but we’ve been cautioned by sources [close to the mediation effort] that there are detractors on all sides,” said Al Jazeera’s Osama Bin Javaid from Doha.

He said the detractors include elements “in Tehran, in Washington, DC, and biggest of them all, according to Pakistani sources, is Israel, which does not want a peace deal and wants a perpetual war in the region”.