Trump wants to withdraw from the INF treaty that was signed over three decades ago by the US and Soviet leaders.

US President Donald Trump has said Washington will withdraw from a 31-year-old nuclear weapons agreement with Moscow, accusing Russia of violating the treaty and demanding the inclusion of China.

Here are five things to know about the Intermediate-Range Nuclear Forces Treaty (also known as the INF treaty):

1. How did the agreement come about?

The INF treaty was signed in December 1987 by the then-US President Ronald Reagan and Soviet leader Mikhail Gorbachev.

It resolved a crisis that had begun in the 1980s with the deployment of Soviet SS-20 nuclear-tipped, intermediate-range ballistic missiles targeting Western capitals.

By signing the agreement, Washington and Moscow swore off from possessing, producing or test-flying a ground-launched cruise missile with a range between 500 and 5,500km.

2. Why is the US withdrawing from the treaty?

US officials believe Moscow is developing and has deployed a ground-launched system in breach of the INF treaty that could allow it to launch a nuclear strike on Europe at short notice.

Russia has consistently denied any such violation.

Trump said on Saturday that it was only fair for US to develop the weapons since Russia and China (not a signatory of the treaty) were already doing it.

3. How does Russia feel about the INF deal?

Moscow has long been accusing the US of violating the nuclear agreement, pointing to a NATO missile shield in Romania that could launch nuclear missiles at any time.

In 2007, Russia even threatened to withdraw from the INF treaty.

On Sunday, an unnamed Russian foreign ministry official told state news agencies that Washington has been “deliberately and step-by-step destroying the basis for the agreement” for many years.

4. What can the US withdrawal from the nuclear treaty lead to?

The move will end the prospect of the renewal of the New Start agreement between Moscow and Washington which is set to expire in 2021, as the INF treaty is its backbone. Signed in 2010, New Start requires both nations to cut their deployed strategic nuclear warheads to no more than 1,550.

Russian Senator Alexei Pushkov wrote on Twitter that the move was “the second powerful blow against the whole system of strategic stability in the world” after Washington’s 2001 withdrawal from the Anti-Ballistic Missile treaty.

Gorbachev, the co-signatory of the INF treaty, said on Sunday it would be a mistake for Washington to quit the deal, and that it would undermine work he and US counterparts did to end the arms race.

5. Can the nuclear deal be saved?

John Bolton, Trump’s national security adviser, is scheduled to meet Russian leaders, including Foreign Minister Sergey Lavrov and Security Council Secretary Nikolai Patrushev, this week in Moscow.

The trip is likely to show whether there is a chance for the deal to be saved. Trump’s announcement on Saturday suggested that he hoped for the re-negotiation of the terms.

Last week, The Guardian reported Bolton, a long-standing opponent of arms control treaties, was pushing for the US withdrawal over alleged Russian violations.

US Defence Secretary James Mattis has previously suggested that a Trump administration proposal to add a sea-launched cruise missile to Washington’s nuclear arsenal could provide the US with leverage to try to persuade Russia to come back in line on the arms treaty.