WASHINGTON (REUTERS) - US Director of National Intelligence Dan Coats said on Thursday (July 19) he does not know what happened in the one-on-one meeting in Helsinki between President Donald Trump and Russian President Vladimir Putin that has raised concern among many US lawmakers.

The lawmakers are seeking answers on what agreements Trump may have reached with Putin in their two-hour meeting on Monday in which they were accompanied only by their interpreters.

The White House has faced an uproar over several issues from the summit, including Trump's failure to confront Putin over Russian meddling in the 2016 election and Putin's proposal that Russian authorities be allowed to question US citizens.

"Well, you're right, I don't know what happened at that meeting," Coats said at the Aspen Security Forum in Colorado.

"I think as time goes by and the President has already mentioned some things that happened in that meeting, I think we will learn more. But that is the president's prerogative," Coats added.

Trump has called the summit "a great success," but he has been vague about what he discussed with Putin.

Terrorism, Israel, nuclear proliferation, cyber attacks, trade, Ukraine, the Middle East and North Korea were among the issues they talked about, Trump said in a tweet on Thursday.

Putin agreed the summit was a success and said on Thursday it "led to some useful agreements," without providing details.