Moreover, recently there is an influential theory that the invasion of Izu Province by Soun HOJO, a vassal of the Imagawa clan, that occurred in the same year, in cooperation with Masamoto and Sadamasa UESUGI, was intended to defeat Chachamaru ASHIKAGA, who was the Horikoshi Governor-General and Yoshizumi's brother by a different mother, and opposed Yoshizumi.
さらに近年では、同年に発生した今川氏家臣北条早雲（北条早雲）の伊豆国侵攻が、義澄と対立関係にあった異母兄である堀越公方・足利茶々丸を倒すために、政元や上杉定正と連携して行われたとする見方が有力になっている。