Yes you can. Especially in your area. Russian tortoises (and other Testudo species) do very well outdoors in the Northeastern U.S. The enclosure needs to be as large as possible and situated in an area that gets sunlight most of the day. It also needs to have at least one shelter that your tortoise can escape the heat during the day. Multiple shelters are better so that your tortoise has choices. The substrate should be a natural or organic soil deep enough for the tortoise to burrow into and completely cover it's body. Drinking water should be available at all times and should replaced at least once daily. Most importantly the enclosure should secure and the sides deep enough so that your tortoise cannot dig under or climb over. Russian tortoises are a true burrowing species, but they are also very good climbers and should never be underestimated. There is no need for night time heat for Russian tortoises whether indoors or outdoors.