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President Donald Trump met privately with North Korea's Kim Jong Un (kim jawng oon), kicking off their two-day nuclear summit in Vietnam.

Two interpreters were the only other people privy to their conversation on Wednesday.

That has raised concerns about why Trump would risk meeting Kim, who has threatened the U.S. with nuclear strikes and has a dismal human rights record, without staff to take notes.

Trump has had private meetings world leaders before.

Early in his presidency, he met Russian President Vladimir Putin in Germany with only a Kremlin interpreter present. Last year, after Trump spent more than two hours talking with Putin in Helsinki, Finland, Democrats tried to subpoena Trump's translator to testify in Congress about what was said.