President Donald Trump told leaders at the G7 summit that Crimea is part of Russia because everyone there speaks Russian, according to diplomatic sources.

The Crimean peninsula was part of Ukraine before being invaded and annexed by Russia in 2014. The annexation led to Russia's expulsion from the G7.

Before the summit, Trump told reporters he believed Russia should be let back into the G8.

President Donald Trump told world leaders at the G7 summit that Crimea, a contested territory south of Ukraine, is part of Russia because everyone there speaks Russian, two diplomatic sources told Buzzfeed.

Trump made the remarks at a Friday night dinner during the recent G7 summit in Québec, Canada, according to one of the sources.

Crimea, a peninsula that juts out from Ukraine into the Black Sea, has been disputed territory for centuries. According to the most recent 2001 census, 58% of people living in Crimea identified as ethnically Russian, and 77% spoke Russian as their main language.

Russian President Vladimir Putin officially invaded and annexed the Crimean peninsula in 2014 with the aid of pro-Russian separatists. The annexation led to international condemnation and sanctions, as well as Russia's expulsion from the G8 group of world leaders, making it the G7.

The diplomatic source also said Trump told world leaders at the dinner that "Ukraine is one of the most corrupt countries in the world" and wondered why leaders sided with them over Russia.

While Russia has claimed Crimean residents as "federal subjects" of Russia, Ukraine contends that Crimea is an integral part of its territory. While about ten UN member states recognize Crimea as Russian territory, the vast majority of the others, including the United States, side with Ukraine in the dispute.

Before departing for this year's G7 summit on Friday, Trump ruffled feathers by telling reporters he believed Russia should be let back in to the G8.

"Whether you like it or not, and it may not be politically correct, but we have a world to run," he said. "And in the G7, which used to be the G8 — they threw Russia out — they should let Russia come back in because we should have Russia at the negotiating table."