Iran has issued a grave warning, with President Masoud Pezeshkian stating that any aggression against Supreme Leader Ayatollah Ali Khamenei would be considered an 'all-out war' against the Iranian nation. This declaration was made on January 18, 2026, via a post on social media platform X, and comes amidst escalating rhetoric between Tehran and Washington. The warning directly followed comments made by former US President Donald Trump, who, in a Politico interview on January 17, 2026, called for 'new leadership' in Iran and described Khamenei as a 'sick man' who should cease the killing of his people. In response to Trump's remarks, Supreme Leader Khamenei had, on January 17, 2026, publicly labeled the former US President a 'criminal,' holding him responsible for casualties and damages during ongoing anti-government protests in Iran. These widespread protests, which began around December 28, 2025, over economic grievances, have since evolved into calls for regime change and have been met with a harsh crackdown by Iranian authorities. Reports indicate thousands of deaths and arrests, although exact figures vary between official Iranian statements and human rights organizations. Iranian officials have consistently blamed the United States and Israel for instigating the unrest and for the economic difficulties faced by its citizens due to longstanding sanctions. The situation highlights a critical juncture in US-Iran relations, with potential global geopolitical ramifications.