Have the United States and Iran blown their best chance of striking a deal to stop Iran acquiring nuclear weapons in exchange for a lifting of sanctions? And, is it now only a matter of time before Iran becomes a nuclear power? The deadline for talks has been extended, but Republicans take control of the US Congress in January and with an election coming up in Iran, those opposed to a deal will have more sway. Hardtalk speaks to Vali Nasr, a Middle East expert who used be an adviser to President Obama's administration. So what is Obama getting so wrong? And could it mean that Iran ends up with nuclear weapons and changes the balance of power in the Middle East?(Photo: Dr Vali Nasr testifies before the Senate Foreign Relations Committee. Credit: Jim Watson/AFP/Getty Images)