The West Asia region was on edge again on Friday night and Saturday morning as Iran's Islamic Revolutionary Guard Corps (IRGC) Navy claimed it had struck US military positions in response to American airstrikes on Iranian coastal areas. The reported retaliation marked the latest escalation threatening a fragile ceasefire reached just days ago. The IRGC's response came after Washington carried out strikes on Iranian targets over attack on a cargo ship earlier.US-Iran ceasefire faces biggest test yet after Hormuz flare-up, both sides launch fresh attacks (X/@CENTCOM)The US military action marks the most serious test of an interim agreement reached just a week ago, under which both sides had agreed to begin efforts to end months of conflict and restore stability in the strategically vital shipping corridor. Track US Iran war news live.The latest escalation began after a drone attack targeted a cargo ship transiting the Strait of Hormuz on Thursday. US President Donald Trump said the attack amounted to a violation of the ceasefire and signalled that Washington was considering a response.“You’ll find out,” Trump told reporters when asked whether the US would retaliate.Hours later, the US launched strikes against what it described as missile and drone sites, along with coastal radar installations in Iran. The operation was confirmed by US Central Command.Speaking at the White House shortly before the strikes, Trump said, “I don’t like the fact that they took a shot yesterday, actually four of them.”When questioned about military action despite his repeated claims that talks with Tehran were progressing well, Trump replied: “They’re a little bit different.”Iran rejects ceasefire violation claimIran swiftly pushed back against the US accusation that the drone attack breached the ceasefire.Ebrahim Azizi, head of the Iranian parliament’s national security commission, defended Tehran’s position and stressed Iran’s authority over the Strait of Hormuz.“The Strait of Hormuz is governed by Iran, so: Respect the rules,” Azizi wrote on social media, adding that others should “not mistake control for escalation.”“This is not a violation of the ceasefire; it is ceasefire management,” he said.Vice President JD Vance later urged Iran to engage through diplomatic channels, warning that Washington would respond firmly to any future attacks.“But violence will be met with violence,” Vance said, while adding that Iran should “pick up the phone” if disputes emerge over the ceasefire arrangement.New communication channelEven as tensions rise, Iran and the US have established a direct communication mechanism aimed at preventing incidents in the Hormuz Strait from spiralling into a broader military confrontation, reported Iranian state news agency, Press TV.The channel was created following talks held in Zurich last week and forms part of the final statement issued by mediators. Its purpose is to reduce the risk of misunderstandings and help implement provisions contained in the Islamabad memorandum of understanding.Iran has maintained that all vessel movements through the strait must follow routes approved by Tehran.Deputy Foreign Minister Kazem Gharibabadi reiterated that position on Friday.“Safe passage through the Strait of Hormuz cannot be guaranteed under ambiguous arrangements, parallel routes or decision-making that does not take Iran’s role as a coastal state into account,” he said.He also warned that Iran could suspend alternative transit routes if ships fail to coordinate with Tehran.Situation in the Strait of HormuzThe dispute centres on one of the world's most important maritime chokepoints. Under the 14-point interim agreement signed on June 18, which halted the conflict triggered by US-Israeli strikes on Iran.Shipping traffic had begun recovering after the ceasefire. On Wednesday, 78 vessels passed through the strait – the highest number since the conflict began, though still below the pre-war average of more than 130 ships a day, reported AP.However, uncertainty over navigation rules has already disrupted maritime traffic. At least two tankers reportedly turned back while attempting to use a UN-backed transit route near Oman after Iran insisted that vessels travel only through Tehran-approved corridors.Despite Thursday's drone attack, more than two dozen ships continued to use the southern route through the strait on Friday.(With AP inputs)