While in the US he negotiated with Capt. Franz von Rintelen of German Navy Intelligence for money to purchase weapons and arrange U-boat landings to provide support, while offering (perhaps as a bargaining chip) to make war on the US, which Germany hoped would end munitions supplies to the Allies. Their meetings, held at the Manhattan Hotel (as well as another New York hotel, "probably the Holland House" at Fifth Avenue and 30th Street), were observed by Secret Servicemen, and von Rintelen's telephone conversations were routinely intercepted and recorded.