Why has Moody’s downgraded the US’ credit rating?

Moody’s has downgraded the US’ credit rating months after US President Donald Trump was sworn in for a second term. It comes as the United States has been witnessing financial and economic uncertainty over Trump’s trade policies. It also comes in the backdrop of the US Congress attempting to pass a bill that makes Trump’s 2017 tax cuts permanent But why did the ratings agency make this move? What does it mean?

Explainers