Vladimir Putin has said Russia’s borders “do not end anywhere” during a live televised awards ceremony for students in Moscow.
On stage, the Russian president asked a nine-year-old boy: “Where does Russia’s border end?” The child answered “at the Bering Strait with the United States”.
Mr Putin then gave his own answer, adding "it was a joke” to applause and laughter from the audience.
The phrase “Russia’s borders” became a top trend on Twitter within minutes.
Ukraine’s ambassador to Finland responded on social media, writing “Russia’s border ends nowhere” alongside an image of a ruined log cabin.
The event was put on by the Russian geographical society, which is headed by Defence Minister Sergei Shoigu.
In July 2014, Mr Putin promised to defend ethnic Russians wherever they lived during a speech to Foreign Ministry employees.
"I would like to make it clear to all, our country will continue to actively defend the rights of Russians, our compatriots abroad, using the entire range of available means - from political and economic to operations under international humanitarian law and the right of self-defence."
The Russian president’s latest comments come amid rising tensions with Europe.
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