The Kremlin on Tuesday labeled US and British allegations of Russian-backed hacking "utterly worthless" and unfounded. Washington and London had warned on Monday of a Russian government-sponsored cyber-attack against internet network infrastructure around the world.

Britain's National Cyber Security Centre, the US Department of Homeland Security and the FBI on Monday issued a joint statement on the attack, which they said began in 2015 and could have laid the groundwork for further cyberattacks in the future.

Germany's Federal Office for Information Security (BSI) on Tuesday said they had reviewed similar cases to the one described by the US and UK.

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What US-UK statement said:

• Hackers backed by the Russian government have exploited "large numbers of" routers and switches around the world since 2015.
• The attack focused on governments, businesses, "critical infrastructure," and internet service providers. The statement did not identify any victims by name.
• The FBI has "high confidence" that the hackers are using the compromised networks to spy, steal intellectual property, and "potentially lay a foundation for future offensive operations."

What the German statement said:

• The BSI is already aware of "concrete cases in Germany, in which the attackers' methods demonstrate strong similarities to those described by the US and UK."
• Such cases were already under investigation; indeed, the BSI stressed that it had "pointed them out many times" in recent years.
• "The vulnerabilities … described in the statement are already several years old and generally known."

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Why say something now? The US and Britain said they wanted to warn organizations that may be affected and call on them to inform authorities if they discover breaches. The joint statement comes at a time of high tensions between Russia and the West.

'Grizzly Steppe': The US Department of Homeland Security separately said the attack was part of a larger Russian-backed operation called "Grizzly Steppe."

Moscow: 'Groundless' and 'unjustified' claims: Russian presidential spokesman Dmitry Peskov said on Tuesday there was no proof behind the claims. "The gist and groundless nature of the charges remains the same. In our viewpoint these unfounded claims are utterly worthless." 

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Ukraine attack: Washington and London blamed Moscow in February for a debilitating 2017 cyberattack against Ukraine called "NotPetya," which also damaged IT devices worldwide.

Bad relations: Tensions are already strained between the two sides. Russia has heavily criticized the US, UK and France for launching airstrikes against Russia-ally Syria, while Washington and London have accused Moscow of responsibility for a nerve-agent attack against a former Russian double agent in southern England.

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