The U.S. military has built up a facial recognition database with more than 7.4million identities and boasts that the technology is a 'game changer', it has emerged.

The vast database covers terrorists in war zones as well as troops from allied nations training with U.S. forces.

According to a government presentation obtained by One Zero, the database had identified thousands of people on a military watchlist in the first half of 2019 alone.

Glenn Krizay, director of the Defense Forensics and Biometrics Agency, told a defense conference in June that 'denying our adversaries anonymity allows us to focus on our lethality'.

Facial recognition: The US military has built up a biometric database with more than 7.4million identities and boasts that the technology is a 'game changer' (file photo)

Promotion: A presentation (above) given by the director of the Defense Forensics and Biometrics Agency boasted that the system 'denies anonymity'

In notes for his presentation, Krizay said facial recognition was 'like ripping the camouflage netting off the enemy ammunition dump'.

The database, officially the Automated Biometric Information System, is also connected to the FBI's own facial recognition database, he explained.

That could allow the U.S. military to search facial recognition data of U.S. citizens as well as enemy combatants.

Authorities say the majority of entries were collected by U.S. and allied troops during the wars in Iraq and Afghanistan.

Soldiers used the technology to establish whether any detainees had criminal histories in the United States.

Undercover North Korean agents, ISIS terrorists and Chinese spies could also be identified using biometrics, Krizay suggested.

Krizay cited Russia's alleged poison plot against a former spy in Britain as one example of where facial recognition had been used to identify suspects.

Two Russians were accused by UK authorities of the assassination attempt against Sergei Skripal in March 2018, although there is no prospect of their extradition.

The database also includes fingerprints, palm prints and iris images for some of the soldiers and terrorists who are listed.

Additions: According to this slide, thousands of individuals on the military's watchlist were matched to biometric data in the first half of this year

Under surveillance: Facial recognition data held by the U.S. military covers terrorists in war zones as well as troops from allied nations training with American forces (file photo)

Krizay told guests at the conference that biometrics could also be used to secure access to military documents and physical space.

'If Wikileaks can obtain over a half a million of our reports, what can the likes of China or Russia do?,' he asked.

He also speculated that artificial intelligence might help the government to collect large amounts of data.

According to one of Krizay's slides, thousands of individuals on the military's watchlist were matched to biometric data in the first half of this year.

Lieutenant General Michael Barbero, a former head of the Joint IED Defeat Organization, described biometric techniques as a 'game changer'.

'These capabilities remove violent extremists' greatest defense - anonymity,' he declared.

However, sharing data with the Department of Homeland Security has proved difficult because they use different computer software.

There have also been a series of concerns about possible racial and gender biases in facial recognition technology.

In 2017 a report warned that China was racing to use its own AI technology to develop superior facial recognition systems.

China's People's Liberation Army has already invested in a range of AI-related projects.