Bridgewater Associates' three Co-Chief Investment Officers said they see "exceptional risks" to U.S. assets under the Trump administration's rapid shift to modern mercantilism that puts "America First."

The hedge fund giant made the comments in a newsletter late Wednesday, raising their growing concerns about a possible U.S. recession and threats to U.S. assets which are dependent on foreign flows.

"We expect a policy-induced slowdown, with rising probability of a recession," the Co-CIOs, Bob Prince, Greg Jensen and Karen Karniol-Tambour said in the newsletter.

Assets like U.S. equities that benefited from massive inflows due to strong economic growth and a proactive Federal Reserve in old days are facing imminent risks, they said.

U.S. stocks tumbled, bonds were sold off and the dollar hit a three-year low after U.S. President Donald Trump's started a trade war this month that upended the global trade order.

Investors are also fearful of a deep hit to asset prices if Trump attempts to fire Federal Reserve Chair Jerome Powell.

In November, Bridgewater Co-CIO Karniol-Tambour said U.S. stocks are a "good thing" to hold following Trump's victory in the presidential election.

The latest comments mark a stark shift from that stance.