The US has officially accused Russia of hacking the Democratic Party

The US Department of Homeland Security and Office of the Director of National Intelligence formally accused the Russian government of hacking Democratic Party organizations in a letter posted online Friday.

The letter says the cyber attacks that targeted US political organizations were "intended to interfere with the US election process." It also accuses senior officials within the Russian government of approving the hacks.

"Such activity is not new to Moscow - the Russians have used similar tactics and techniques across Europe and Eurasia, for example, to influence public opinion there," the letter said. "We believe, based on the scope and sensitivity of these efforts, that only Russia's senior-most officials could have authorized these activities."

Leaked emails from Democratic Party officials have appeared on Wikileaks and the website DCLeaks.com in recent months.

The condemnation came amid escalating tensions between Washington and Moscow over a range of international disagreements, including US charges that Russian air strikes in support of embattled Syrian President Bashar al-Assad have been hitting hospitals and other civilian targets in rebel-held eastern Aleppo.

Reuters contributed to this report.