Russia's lower house of parliament, the Duma, on Tuesday voted in favor of withdrawing the ratification of the Comprehensive Nuclear Test Ban Treaty (CTBT).

Duma speaker Vyacheslav Volodin said earlier this month that the move would be a "mirror response" to the United States, which never formally ratified the treaty.

Why is the vote taking place now?

"In the interests of ensuring the security of our country, we are withdrawing the ratification of the Comprehensive Nuclear Test Ban Treaty," Volodin said ahead of a debate and parliamentary vote on revoking ratific

Lawmakers unanimously approved the bill in its first reading. It can be signed into law by Putin after passing three lower house readings and receiving approval in the upper house.
Russian President Vladimir Putin earlier this month suggested that Russia revoke ratification of the treaty because the United States, alongside other powers, had never ratified it.

Putin also said he was "not ready to say" whether Russia might find it necessary to carry out live nuclear tests. 

Who has signed and ratified?

In total, 187 states have signed the treaty and 178 have ratified it legally in their parliaments.

Of the nine countries that possess nuclear weapons, the United Kingdom, France and Russia have signed and ratified.

The United States, Israel and China have signed the document, but not ratified it.

Meanwhile, India, Pakistan and North Korea have neither signed nor ratified the treaty.

The CTBT bans "any nuclear weapon test explosion or any other nuclear explosion" anywhere in the world. Any resumption of nuclear tests could precipitate a new nuclear arms race between the big powers.

In the preamble to the treaty, the goal of reducing and ultimately eliminating nuclear weapons is highlighted.

The intention was to do this "by constraining the development and qualitative improvement of nuclear weapons and ending the development of advanced new types of nuclear weapons, constitutes an effective measure of nuclear disarmament and non-proliferation in all its aspects."

rc/wmr (Reuters, IFAX)