My ex wife isn't a us citizen can she claim my pension

You refer in your post to your “ex-wife.” If you are already divorced presumably your pension would have been dealt with in your divorce decree. If you are simply referring to your wife, rather, as your (soon to be ex wife), I know nothing in the Wisconsin divorce code as to why your pension wouldn’t be fair game in your divorce, whether she is a U.S. citizen or not. Under Wisconsin law, all property acquired either before or during the marriage is subject to equal property division. The only property that is exempt, is property acquired by gift or inheritance.      I can also surmise if your wife is not a United Stares citizen, that you must be married a relatively short period of time. The court has authority to deviate from equal property marriage based on the length of the marriage and property brought into the marriage by either party, along with the relevant other factors under the property division statute.