U.S. Treasury yields stumbled from their recent highs on Friday after President Donald Trump announced on his Truth Social platform his intentions to ramp up the trade war.

The 30-year Treasury yield was down 8 basis points at 4.988%. The 10-year Treasury shed 10 basis points to 4.457%. The 2-year yield moved 3 basis points lower to 3.968%.

One basis point is equivalent to 0.01%, and yields move inversely to prices.

Investors are concerned about Trump's "big, beautiful bill," which members of the House of Representatives passed on Thursday. It is yet to be cleared by the Senate. The bill will add nearly $4 trillion to the already massive fiscal deficit, per the Congressional Budget Office.

That has put pressure on U.S. Treasurys and sent yields higher over the past few days, as questions arise over whether Treasurys are still a safe haven asset.

Those fears were amplified especially after Moody's downgraded the U.S.' credit rating by one notch last Friday, bringing it down to the second-highest level, citing the growing budget deficit and the cost of funding the existing debt.

"Even if the inability to reduce the deficit in the U.S. doesn't lead to default, a large deficit still implies greater bond supply, and perhaps eventual inflation as the debt is monetized to avoid default," said Thierry Wizman, global rates and currencies strategist at Macquarie. "Either way, it makes nominal fixed-income instruments less attractive as long-term investments."

Some positive news came amid the bleak picture on Thursday, with the Supreme Court strongly suggesting in a ruling that Federal Reserve board members would have greater protection from being fired by a president, easing fears that Federal Reserve Chair Jerome Powell will be ousted.

— CNBC's Brian Evans contributed to this report.