US President Donald Trump on Thursday said the killing of American troops would be a red line that could swiftly bring an end to the fragile ceasefire with Iran, as Tehran signalled it would continue targeting US military bases in the region.US President Donald Trump during a coal announcement in the Oval Office of the White House in Washington, DC, US. (Bloomberg)When asked by a reporter at the White House whether the killing of US troops would be his red line for ending the ceasefire, Trump replied, “If they killed US troops, that would be a good reason [to end the cease-fire]. If they killed US troops, I think I would do that very quickly".Follow here for live updates on US-Iran warIran continues strikes against USTrump’s warning came as Iran appeared determined to continue strikes against US forces in the region.Iranian Foreign Minister Abbas Araghchi on Thursday sought to justify Tuesday night's strikes on Kuwait that targeted American troops but also killed a Kuwaiti civilian and wounded dozens of others, a New York Post report said.“We had previously warned regional countries about the United States using their bases,” he told IRGC-affiliated media. “Our response is directed at American bases and not the territory of regional countries.”“Many regional countries opposed the use of their airspace and territory against Iran. Unfortunately, the United States used these facilities against us,” he added.Also Read | Trump-Netanyahu rift out in open: 'Crazy' admission, 'tactical disagreements' in focus amid Iran warWhat is happening?Since the February 28 war on Iran began, 13 US service members have been killed in Operation Epic Fury.Seven died in Iranian strikes on US forces, while six were killed when their aircraft crashed over Iraq during refuelling operations.However, since the US and Iran entered into a fragile ceasefire on April 8, no American military personnel have been killed, despite continued exchanges of fire.According to the NY Post, while the administration has not formally directed the military on how to respond to a fatal attack, it is understood that any American death could exhaust Trump's remaining patience.Trump had on Wednesday played down the barrage of 13 ballistic missiles and 17 drones launched at Kuwait, saying that “in that part of the world, ‘cease-fire’ is when you’re shooting in a more moderate manner.”But, according to the report, the death of an American service member would fundamentally alter his calculations, the report added.