Pakistan's powerful army chief arrived in Tehran on Friday as diplomacy around the Middle East war gathered pace, with Iran weighing a new US peace proposal while warning that deep divisions still stand in the way of a deal.Iran's foreign ministry spokesman Esmaeil Baqaei cautioned that the visit did not mean "we have reached a turning point or a decisive situation."The disagreements between Iran and the United States remained "deep and extensive", he added, according to Iran's ISNA news agency.US Secretary of State Marco Rubio had earlier voiced hope of progress toward ending the war, which began on February 28 with US-Israeli strikes on Iran.An April 8 ceasefire halted open fighting, but negotiations -- including historic face-to-face talks in Islamabad -- have yet to produce a lasting agreement.President Donald Trump has described the stop-start negotiations as teetering on the "borderline" between a deal and renewed attacks.Pakistan's military said Field Marshal Asim Munir had "arrived in Tehran as part of ongoing mediation efforts".He was welcomed by Iran's Interior Minister Eskandar Momeni and Pakistan's Mohsin Naqvi.Naqvi had visited Iran for the second time in a week on Wednesday, meeting President Masoud Pezeshkian and Foreign Minister Abbas Araghchi.Baqaei said a Qatari delegation also met Iran's foreign minister Friday."In recent days, many countries -- both regional and non-regional -- have been trying to help bring the war to an end...However, Pakistan remains the official mediator," he added.Pakistan hosted in April the only direct US-Iran talks since the war began.Munir played a central role in that round, greeting both delegations and showing public warmth with US Vice President JD Vance.But the talks failed, with Iran accusing Washington of making "excessive demands". Since then, the two sides have traded proposals under the constant threat of renewed war.- Hormuz squeeze -Rubio, speaking on the margins of a NATO meeting in Sweden, said there had been "some progress" in the talks, but warned that Washington was "not there yet".