Obama calls for nuclear-free world

Barack Obama has promised that the US will do all it takes to achieve a world without nuclear weapons.
In a major speech on Sunday in Prague, the capital of the Czech Republic, the US president said Washington would take "concrete steps" to reduce its nuclear arsenal and encourage other nations to do the same.
He said countries needed to co-operate and have patience to achieve a nuclear-free world.
"Today the Cold War has disappeared but thousands of those weapons have not," Obama said in front of thousands of Czechs at a square in front of the Prague Castle.
"More nations have acquired these weapons, tests continue ... the knowledge to build these weapons has spread.
"If we say to ourselves that the spread of nuclear weapons is inevitable we are saying that the use of nuclear weapons is inevitable."
Obama, in Prague as part of an eight-day visit to Europe, was due to travel to Turkey later on Sunday.

Nuclear energy bank
Obama said the US will seek ratification of the comprehensive test ban treaty on nuclear weapons.
He proposed a nuclear energy bank that nations could access to meet their requirements. The banks in turn would prevent them from using other nuclear materials that could potentially be used to make bombs.
He said that nations should have access to nuclear power for peaceful reasons to combat climate change and to allow people a way out of poverty.
Obama also said that the US would host a summit to discuss the "locking down" of loose nuclear materials, before the end of the year.
In reference to North Korea and Iran, he said that nations who break the rules of nuclear proliferation must be punished.
He said that if Iran continued with its nuclear programme, which many suspect is for weaponry rather than Tehran's stated goal of nuclear energy, the US would build a proposed missile defence shield in Eastern Europe.
'If the Iranian threat is eliminated we will have stronger basis for security and the driving force for missile defence construction in Europe will be removed," he said.
Obama's speech came hours after North Korea launched a satellite into orbit on a rocket that has the capacity to carry nuclear warheads long-range.
Rob Reynolds, Al Jazeera's correspondent in Prague, said: "He's going to try to lead by example ... and rally international support for renewed anti-nuclear weapons steps.
"More concretely he is going to, and has already begun engaging the Russians to restart nuclear arms reduction and limitation talks with a view towards having a treaty on that subject completed before the end of the year."