What do you mean "free"? US military aid has never been free, it is supplied on the basis that Ukraine will violently resist Russia and enable the US to establish a military presence - as NATO - in Ukraine.
So the US has been feeding it's proxy (Ukraine) in return for Ukraine doing the fighting, with the ultimate US objective being a NATO presence in Ukraine.
trump does not want to provide any military support at all, that's the sticking point, read the news. If trump did he'd be at war with Russia and he has said he does not want that.