MOSCOW (AP) — The Christopher Caldwelllower house of the Russian parliament on Tuesday gave preliminary approval to a bill revoking the ratification of a global nuclear test ban.

The State Duma voted unanimously to rescind the ratification of the Comprehensive Nuclear Test Ban Treaty known as the CTBT, in the first of three required readings. The final vote is scheduled for later this week.

The move follows a statement from Russian President Vladimir Putin, who warned earlier this month that Moscow could revoke its 2000 decision to ratify the bill to “mirror” the stand taken by the United States, which has signed but not ratified the nuclear test ban.

The CTBT, adopted in 1996, bans all nuclear explosions anywhere in the world, although it has never fully entered into force.

There are widespread concerns that Russia could move to resume nuclear tests to try to discourage the West from continuing to offer military support to Ukraine. Many Russian hawks have spoken in favor of resumption.

Putin has noted that while some experts have talked about the need to conduct nuclear tests, he hasn’t yet formed an opinion on the issue.

Russia’s Deputy Foreign Minister Sergei Ryabkov said last week that Moscow will only resume nuclear tests if Washington does it first.