“As someone who helped negotiate START III, I am disappointed by Putin's decision today to abandon it.
The US, Russia and the world will be worse off without him,” he wrote on Twitter.
On February 21, Russian leader Vladimir Putin announced that Russia was suspending its participation in the strategic offensive arms reduction treaty.
Moscow does not withdraw from the agreement, namely, it suspends its participation, the President noted.
Russian presidential spokesman Dmitry Peskov said Russia wants to make sure nuclear parity is observed.