"… that you say you want to block proliferation nuclear arms is a big lie and even the US administration's performance in the last few days has been a big lie as well," Ahmadinejad said on Friday, addressing a ceremony to mark the "National Day of Nuclear Technology" in Iran.
US President Barack Obama and his Russian counterpart Dmitry Medvedev signed the agreement Thursday in Prague. It envisages shrinking the US and Russian nuclear warhead limit by about a third, to 1,550.
The reduction to 1,550 is 74% lower than the limit set in the original START deal and 30% lower than the one established under the 2002 Moscow Treaty.
Noting that stockpiling nuclear weapons by the US and certain world powers is an incentive for other countries to develop such arms, the Iranian president reiterated, "When we ask them why they store nuclear weapons and if they intend to use them against (other) nations, they say 'we have stored them for deterrence'."
"If nuclear weapons are deterrent, firstly, why don't others have them as everyone likes to enjoy a deterrent power. Secondly, the policy leads to a serious competition among rivals on nuclear weapons as everyone wants to have the upper hand to be deterrent and if anybody has the lower hand, he cannot be deterrent," he added.
Referring to Obama's recent remarks on Washington's new nuclear strategy, Ahmadinejad asked if a person who threatens to use nuclear weapons against others can prevent proliferation and spread of nukes or he would cause further proliferation.
The United States pledged never to use nuclear weapons against the states that comply with the Non-Proliferation Treaties (NPT) as part of a much-anticipated review of nuclear arms strategy released Tuesday.
But the new pledge leaves open a nuclear strike against countries that have signed on to a global NPT but stand accused of violating its terms.
Obama, in an interview with the New York Times, said outright that the loophole would apply to "outliers like Iran and North Korea" that the US believes are developing nuclear weapons.
In response, President Ahmadinejad said that American leaders still act like cowboys and like heroes in Western movies, "Whenever there is a problem, they take out their guns."