dont help italy. let them die to the british. you can hold the italian alps indefinitely. tell him the specs for the assault rifle. tell him the specs for a modernized panther.  tell him the specs for the panzerfaust but with greater range. tell him the specs for jet fighters and air to air missiles using radar guidance tell him artillery is the biggest killer and that small unit firepower for numerically small yet heavily entrenched heavy infantry is the key to defeating the ussr. i personally dont know how to build nukes but i can tell him how to build surface to air missiles, build an aa screen to prevent all allied bombers. tell him how to build guided torpedos to prevent the royal navy from entering the channel. tell him to build the mg42 early. tell him to build the fg42 early. you will deploy fallschirmjeagers with fg42s and panzerfausts to england in a first strike attack, resupply them via submarine. instruct him to deploy long range guided torpedos which can fired from a mile away and make submarines virtually invincible if they arent ambushed. set up an initiative to deport all jews in europe to israel and offer them gold and guns in exchange for torpedoing the british war effort.  remove all jews post war.
United States