A visibly emotional Barack Obama rejected growing clamour for a US-led ground invasion of Syria on Monday in the most passionate defence yet of his strategy of trying to contain Islamic State extremists rather than treating them as a conventional enemy. “It’s best that we don’t shoot first and aim later,” said the US president during an intense press conference at the G20 summit in Turkey that saw reporters urging him to “take out these bastards.” “If folks want to pop off and have opinions about what they want to do, present a specific plan,” said an unusually angry Obama. “What I am not interested in doing is posing, or pursuing some notion of American leadership or America winning or whatever other slogans they come up with ... I’m too busy for that.”