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United States President Barack Obama's momentous decision on Thursday to scrap plans to install a controversial missile defense shield in Eastern Europe has been praised by Russia and a number of European countries. But in Iran, the announcement has triggered worrying questions about why, and why now?

Washington denies that any secret deal has been made with Moscow. Still, some analysts point to the possibility the US shelved planned anti-missile interceptors in Poland and a huge radar in the Czech Republic in exchange for the Kremlin abandoning its reluctance to exert pressure on Iran over its nuclear program. If this was Obama's...