His negotiation with Kenshin UESUGI and Katsuyori TAKEDA in addition to the enactment of alliance with Ieyasu TOKUGAWA, the Date clan from Oshu (Mutsu Province) and the Ashina clan after the death of Nobunaga ODA implies an exertion of his ability of diplomacy.
上杉謙信や武田勝頼との折衝や、織田信長没後の徳川家康、奥州の伊達氏、蘆名氏との同盟の成立には、その外交手腕が発揮されたと読み取ることができる。