Why is the US involved in negotiations between Russia and Ukraine?

Trump and his allies have repeatedly argued that the US should stop getting involved in other countries' wars, taking an "America First" policy that emphasizes stepping back from global conflicts.

So why is the Trump administration playing a key role in brokering peace between Russia and Ukraine? Wouldn’t a true non-interventionist stance mean withdrawing aid from Ukraine and stepping back to let Ukraine and Russia negotiate directly, while the US tends to its own interests at home?