Russia and the US reached an outline arms agreement in July
Russia will continue developing new nuclear missiles and launchers despite disarmament talks with the US, Russia's President Dmitry Medvedev says.
"Of course, we will develop new systems, including delivery platforms, or missiles. This is routine practice, the entire world is doing it," he said.
Speaking in a live TV interview, Mr Medvedev said this would not bypass agreements with the US.
Russia says it successfully tested a long-range SS-18 missile on Thursday.
The missile - called an RS-20 Voyevoda in Russia - was fired from Orenburg in central Russia and hit targets in Kamchatka, in the far east, the Ria Novosti news agency reported.
New treaty plan
So far Russia and the US have failed to find a successor to the Cold War-era Start 1 treaty. That treaty, which led to deep cuts in nuclear arsenals on both sides, expired on 5 December.
Asked why there had been a delay, Mr Medvedev said "this is a difficult question, a very difficult one".
"This is a treaty which determines the parameters for developing and reducing the strategic arms potential of two of the biggest nuclear states. We are moving very quickly as it is. We have agreed on almost everything."
Both sides have agreed to continue observing Start 1 - which was signed by Mikhail Gorbachev and George Bush Senior in the final days of the Soviet Union - until they reach a new agreement.
Under a joint understanding signed in July, deployed nuclear warheads should be cut to below 1,700 on each side within seven years of a new treaty - a huge cut on Soviet-era levels.
Nonetheless, between them the two countries will retain enough firepower to destroy the world several times over.