The US has expelled 35 Russian diplomats as
punishment for alleged interference into last
month's presidential elections, giving them 72
hours to leave the country.
It will also close two compounds used for
Russian intelligence-gathering.
President Barack Obama had vowed action
against Russia amid US accusations it directed
hacks against the Democratic Party and Hillary
Clinton's campaign.
Russia has denied any involvement and called the
decision "ungrounded".
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The US state department declared the 35 Russian
diplomats from the Washington DC embassy and
the consulate in San Francisco "persona non
grata", and gave them and their families 72 hours
to leave the US.
The move follows calls from senior US senators
to sanction Russian officials who are believed to
have played a role in the hacking, which some
lawmakers referred to as America's "political
Pearl Harbor".
Republican senators John McCain and Lindsey
Graham, who led the calls for sanctions, said they
"intend to lead the effort in the new Congress to
impose stronger sanctions on Russia".
A Kremlin spokesman told journalists in Moscow
that President Vladimir Putin would consider
retaliatory measures.
Dmitry Peskov said the actions were "a
manifestation of unpredictable and aggressive
foreign policy", and called them "ungrounded and
not legal".
And the Russian embassy in the UK tweeted a
visual gag calling the Obama presidency a lame
duck.
President-elect Donald Trump, who will take over
from President Obama next month, has dismissed
the hacking claims as "ridiculous" and said
Americans should "get on with our lives " when
asked about the possibility of sanctions before
the announcement on Wednesday.
Sanctions have also been announced against nine
entities and individuals including Russian
intelligence agencies, the GRU and the FSB.
Russian intelligence compounds in New York and
Maryland will be closed.
'Necessary and appropriate'
In a statement, President Obama called the
moves a "necessary and appropriate response to
efforts to harm US interests" and said "all
Americans should be alarmed by Russia's
actions".
Mr Obama also announced the US would
declassify technical information related to
Russian cyber activity to "help network defenders
in the United States and abroad identify, detect,
and disrupt Russia's global campaign of
malicious cyber activities".
Speaker of the House Paul Ryan, the top
Republican in Congress, said in a statement that
despite the measures being overdue "it is an
appropriate way to end eight years of failed policy
with Russia".
Democratic Senator Ben Cardin, who is from
Maryland, called for Congress to take action
separately from the White House, and plans to
introduce legislation to establish a committee "to
further examine the attack and Russian's efforts
to interfere in our election".
'A decade-long campaign'
In a joint statement by the Department of
Homeland Security, the Office of the Director of
National Security, and the FBI, US officials appeal
to companies to "look back within their network
traffic" and report any signs of "malicious cyber
activity" to law enforcement.
The Russian hacking, which the US intelligence
agencies describe as a "decade-long campaign"
included methods such as "spearphishing,
campaigns targeting government organisations,
critical infrastructure, think-tanks, universities,
political organisations, and corporations; theft of
information from these organisations; and the
recent public release of some of this stolen
information".
Emails stolen from Hillary Clinton's campaign
manager and from the servers of the Democratic
National Committee were released during the
2016 presidential election by Wikileaks.
Several US agencies, including the FBI and CIA
have concluded that the hacked information was
released to cause damage to Mrs Clinton and the
Democrats in order to favour Mr Trump.
