What is the burden of proving that Charley's injuries were not intentional, knowingly, or recklessly caused by careless or reckless striking?

⁷ The district court instructed the jury that the Government carried the burden to prove that "[Charley] assaulted [Begay] by intentionally, knowingly, or recklessly striking or wounding him." "[T]he common law definition of assault, a general intent offense that requires a showing of willfulness, has been incorporated into the federal offense of assault resulting in serious bodily injury, 18 U.S.C. 113(a)(6)." United States v. Garcia-Jimenez , 807 F.3d 1079, 108586 (9th Cir. 2015).