President Donald Trump. Mark Wilson/Getty Images President Donald Trump once called National Security Adviser Mike Flynn at 3 a.m. to ask about the economic impact of a strong US dollar, according to a report from The Huffington Post.

SV Date and Christina Wilke, citing sources with knowledge of the conversation, reported that Trump asked Flynn whether the strong dollar was good or bad for the US economy during the early-morning phone call. According to the sources, Flynn said he was not sure and Trump should ask an economist instead.

The Huffington Post said neither Flynn's office nor the White House responded to its request for confirmation of the call's timing. The White House did not immediately return a request for comment from Business Insider.

Trump and his team have generally said the stronger dollar, which strengthened significantly against other major currencies after the election but has since given back some of its gains, has been a negative for the US economy.

In an interview with The Wall Street Journal, Trump said the strong dollar was "killing us."

"Our companies can't compete" with Chinese companies Trump said, "because our currency is too strong."

Trump's pick for Treasury secretary, Steven Mnuchin, said in January that while a stronger dollar was generally good for the US because it represented "faith that investors have in doing business in America," the current strength of the dollar could have "negative short-term implications on the economy."

Recently, Trump's team has attacked China and Germany for what it believes are improper tactics to devalue their currencies against the dollar.

A strong dollar is generally good for American consumers because it makes it cheaper for people to buy foreign-made products, but it can also hurt US-based producers that export their goods, which become more expensive in other countries.

The US dollar index is little changed on Wednesday, higher by 0.3% at 100.50.