武装部队严阵以待，随时准备“扣动扳机”，伊朗强硬回应美“最后通牒”

Group 1 - The core message of the articles revolves around escalating tensions between the United States and Iran, with President Trump issuing a "last ultimatum" to Iran, warning of potential military action if negotiations do not occur [1][2] - Trump emphasizes the urgency for Iran to negotiate a mutually beneficial agreement, threatening more severe actions than previous military strikes if Iran does not comply [2] - Iran's Foreign Minister, Zarif, asserts that the Iranian armed forces are prepared to respond forcefully to any aggression, indicating a readiness for both negotiation and conflict [1][2] Group 2 - The deployment of a significant U.S. naval presence in the Middle East, including the USS Lincoln aircraft carrier and at least 10 other ships, underscores the seriousness of the U.S. military posture in the region [2] - Iranian officials, including Speaker Ghalibaf, express skepticism about U.S. intentions, suggesting that while Iran is open to dialogue, past experiences indicate that U.S. actions are more about coercion than diplomacy [2][3] - The potential for U.S. regime change in Iran is discussed, with U.S. officials acknowledging the complexity of such an endeavor compared to previous interventions in Venezuela [4][6]