President Donald Trump faced one of the most monumental decisions of his presidency on Tuesday as he debated whether to join a war against Iran that risked sucking Washington into a new Middle Eastern conflict but also offered the chance to eliminate a rival’s nuclear program.

In the span of about eight hours, President Donald Trump went from suggesting a nuclear deal with Iran remained “achievable” to urging Tehran’s 9.5 million residents to flee for their lives as he cut his visit to the international G7 summit short.