Iran has warned the United States of retaliation if subjected to military aggression, saying all US bases and assets in the region would become “legitimate targets” in such a scenario.In a strongly worded letter addressed to the UN secretary general, António Guterres, and members of the security council, Iran accused the United States of issuing unlawful threats of force and urged the Council to act “without delay” to prevent further escalation.While reiterating that it “neither seeks tension nor war” and will not initiate any conflict, Iran made clear that it would respond if attacked.“In the event that it is subjected to military aggression, Iran will respond decisively and proportionately in the exercise of its inherent right of self-defence under Article 51 of the Charter of the United Nations,” the letter stated.It added that in such circumstances, “all bases, facilities, and assets of the hostile force in the region would constitute legitimate targets” as part of Iran’s defensive response. Tehran said the United States would bear “full and direct responsibility” for any “unpredictable and uncontrolled consequences.”Iran urged the security council to use its authority and good offices to ensure that the US “immediately ceases its unlawful threats of the use of force.”Tehran also said it noted that it has engaged “constructively, with seriousness and in good faith” in nuclear talks with the US.The warning to the UN comes against a backdrop of rising military posturing and hardening rhetoric on both sides.On Thursday, Iran conducted its annual military drills with Russia, even as a second US aircraft carrier moved closer to the Middle East — a visible reminder of the growing strategic pressure in the region. The developments have underscored the fragile situation between both Washington and Tehran, as the two nations signal that they are prepared for conflict if nuclear negotiations collapse.US President Donald Trump has repeatedly cautioned Iran that failure to reach a deal would carry consequences. In his latest remarks, he suggested the window for diplomacy may be closing fast, saying he believes 10 to 15 days is “enough time” for Iran to reach an agreement.“It’s proven to be, over the years, not easy to make a meaningful deal with Iran, and we have to make a meaningful deal. Otherwise, bad things happen,” Trump said on Thursday.While there has been no official indication of imminent military action, the convergence of diplomatic deadlines, visible force deployments and escalating rhetoric has kept tensions high, placing US-Iran relations under intense international scrutiny.