The US State Department published on Tuesday the number of nuclear warheads the country stockpiles for the first time in four years, after former president Donald Trump placed a blackout on the data.

As of September 30, 2020, the US military maintained 3,750 active and inactive nuclear warheads, down by 55 from a year earlier and by 72 from the same date in 2017. 

The figure was also the lowest level since the US nuclear stockpile peaked at the height of the Cold War with Russia in 1967, when the total was 31,255 warheads.

The numbers were released Tuesday amid an effort by the administration of President Joe Biden to restart arms controls talks with Russia after they stalled under Trump.

"Increasing the transparency of states' nuclear stockpiles is important to nonproliferation and disarmament efforts," the State Department said in a statement.

Trump, who pulled the United States from the Iran nuclear deal and the Intermediate-Range Nuclear Forces (INF) treaty with Russia, also left another crucial pact, the New Start Treaty on the rocks last year before its scheduled expiration on February 5.

New Start caps the number of nuclear warheads held by Washington and Moscow, and letting it expire could have sparked a reversal of warhead reductions on both sides.

Trump said he wanted a new deal that includes China, which only has a fraction of the warheads that the United States and Russia have.

Biden, who came in to office on January 20, immediately proposed a five-year extension to New Start, which Russian President Vladimir Putin quickly agreed to.

The deal caps at 1,550 the number of nuclear warheads that can be deployed by Moscow and Washington.

Last week Russian and US diplomats held talks behind closed doors in Geneva to begin discussions on a successor to New Start and also controls on conventional weapons.

A US official called the talks "productive," but both sides said the mere fact of holding the talks was positive.

According to a January 2021 tally by the Stockholm International Peace Research Institute, which includes retired warheads -- not counted in the State Department's numbers -- the United States had 5,550 warheads, compared to 6,255 in Russia, 350 in China, 225 in Britain, and 290 in France.

India, Pakistan, Israel and North Korea have together around 460 nuclear warheads, according to the institute.