In the middle of an Easter lunch at the White House, President Donald Trump went off script to address speculation about JD Vance's role in securing a deal to end the war in Iran. "If it doesn't happen, I'm blaming JD Vance," Trump joked, drawing laughter at last week's East Room event attended by senior administration officials including the vice-president, Secretary of State Marco Rubio, and Defence Secretary Pete Hegseth. And "if it does happen," Trump added, "I'm taking full credit." The remarks perfectly captured Vance's predicament as he leads a US delegation holding talks with Iran in Pakistan. It...