William Alberque has more than 25 years of experience in arms control and disarmament issues.

He previously served as Head of NATO's Arms Control and Disarmament Department (ACDC) and is now Head of Arms Control at the UK IISS.

Alberque says Putin's statement about a "pause" from the bilateral New Start agreement between the US and Russia is deeply troubling.

- It is a terrible development for security on both sides.

Russian intercontinental ballistic missile Yars is reportedly being tested in Kura, Russia, during a nuclear weapons exercise.

Photo: Russian Ministry of Defense February 19, 2022

"Pause" does not exist

Alberque emphasizes that there is nothing that can be called a "pause" in the New Start agreement.

Either you're in or you're not.

The US does not recognize the term "pause" - unless it is described in an agreement.

The Kremlin's announcement likely means that Russia is now putting a definitive end to both sides' controls on each other's strategic nuclear weapons.

- What this means is that Russia will not send or receive any inspections/inspectors.

They will no longer send any intelligence, which is the lifeblood of the treaty, says William Alberque.

He emphasizes that US and Russian arms controls are important instruments to create calm on both sides and avoid misunderstandings.

A Russian Topol-M intercontinental ballistic.

Photo: AP archive image

Will be valid until 2026

The current agreement is valid until 2026, and the announcement from Putin means that both sides can greatly increase the number of operational nuclear weapons in a short period of time.

- This means we can go from the two sides deploying 1,550 strategic warheads each, to both sides deploying as many as 4,000 or 5,000 each.

And this could happen within months, because they have warheads in storage that can be moved to active nuclear arsenals.

So it's a very bad situation.

Sipri: "Deliberate uncertainty"

Dan Smith, who is director of Stockholm's international peace research institute, Sipri, says he is not surprised by Putin's announcement.

The Kremlin intends to destabilize.

- Although President Putin has not withdrawn Russia from the treaty, he has created uncertainty.

This is probably intentional, but it can also be dangerous in today's atmosphere of heightened hostility.

Here you can explore the world's nuclear forces.