DUBAI/WASHINGTON: Pakistan stepped up diplomacy on Thursday to hasten U.S. and Iran peace talks as Tehran hardened its stance on the nuclear issue and U.S. President Donald Trump threatened new strikes if he did not receive the "right answers."
Six weeks since a fragile ceasefire took effect, talks to end the war have made little progress, while soaring oil prices are stoking inflation and straining the global economy.
Trump also faces domestic pressure ahead of November's midterm elections, with his approval rating near its lowest since he returned to the White House due to the fuel price surge.
Pakistan's Army Chief Asim Munir will decide on Thursday whether to travel to Tehran for mediation, three sources familiar with the negotiations told Reuters.
They sought anonymity because they were not authorised to speak to media. Pakistan's interior minister was in Tehran on Wednesday.
"We're speaking to all the various groups in Iran to streamline communication and so things pick up pace," said one of the sources.
"Trump's patience running thin is a concern, but we're working on the pace at which messages are relayed from each side."
Iran's ISNA news agency said Munir would travel to Tehran on Thursday for consultations. The text being discussed in Tehran is on the general framework, and some details and confidence-building measures as guarantees, the agency said.
However, two senior Iranian sources told Reuters that Tehran had toughened its position against one of the main U.S. demands over the nation's nuclear programme.
Supreme Leader Ayatollah Mojtaba Khamenei has issued a directive that Iran's near-weapons-grade uranium should not be sent abroad, the sources said.
US READY TO ACT FAST, TRUMP SAYS
Trump said on Wednesday he was willing to wait for a response but was also ready to resume strikes.
"Believe me, if we don't get the right answers, it goes very quickly. We're all ready to go," Trump told reporters.
Asked how long he would wait, Trump said, "It could be a few days, but it could go very quickly."
Iran's Revolutionary Guards have warned against renewed attacks. "If aggression against Iran is repeated, the promised regional war will extend beyond the region this time," it said in a statement.
Iran submitted its latest offer to the U.S. this week.
Tehran's descriptions suggest it largely repeats terms Trump previously rejected, including demands for control of the Strait of Hormuz, compensation for war damage, lifting of sanctions, release of frozen assets and the withdrawal of U.S. troops.
CHINESE TANKERS CROSS STRAIT
The Strait of Hormuz, which carried a fifth of global shipments of oil and liquefied natural gas before the war, has been all but closed since it began, causing the most serious disruption to global energy supplies in history.
On Wednesday, Iran released a map showing a "controlled maritime zone" at the strait and said transit would require authorisation from an authority set up to control the area.
It said it aimed to reopen the strait to friendly countries that abide by its terms. That could potentially include fees for access, which Washington says would be unacceptable.
Two Chinese supertankers carrying a total of about 4 million barrels of oil exited the strait on Wednesday, while a South Korean tanker with 2 million barrels of crude loaded in Kuwait was also crossing the strait in cooperation with Iran.
Iran said 26 ships had crossed in the past 24 hours, still only a fraction of the 125 to 140 daily passages before the war.
U.S.-Israeli bombing killed thousands of people in Iran before the ceasefire.
Israel has also killed thousands more and driven hundreds of thousands from their homes in Lebanon, which it invaded in pursuit of the Iran-backed Hezbollah armed group.
Iranian strikes on Israel and neighbouring Gulf states have killed dozens of people.
Trump and Israeli Prime Minister Benjamin Netanyahu said their war aims were to curb Iran's support for regional militias, dismantle its nuclear programme, destroy its missile capabilities and make it easier for Iranians to topple their rulers.
But Iran has so far retained its stockpile of near-weapons-grade enriched uranium, and its ability to threaten neighbours with missiles, drones and proxy militias.
It has already restarted some drone production during the ceasefire, CNN said on Thursday, citing two sources familiar with U.S. intelligence assessments.
Iran's clerical rulers, who put down a mass uprising at the start of the year, have faced no sign of organised opposition since the war began.