Vladimir Putin has said he does not see the conditions for the use of nuclear weapons as set out in Russia's nuclear doctrine - but added he could not rule out a change to the doctrine.
"We have a nuclear doctrine which states that the use of nuclear arms is possible in an exceptional case, when the sovereignty and territorial integrity of our country is threatened," he told the St Petersburg International Economic Forum.
"But the doctrine can be changed.
"The same applies to nuclear tests. We will carry out tests if needed, but so far there is no such need."
