The US has halted aid to Ukraine, what next?

The US has halted aid to Ukraine, what next?
The US had been Ukraine's main military supplier since Moscow launched its offensive in February 2022.
Now, US President Donald Trump has suspended military aid to Kyiv.
Trump's stunning decision has strengthened fears in Ukraine and in many European capitals that America is pivoting away from its allies, and towards Moscow.
Why has Trump decided to freeze aid to Ukraine, and what could happen next?