Referring back to the taste for violence, bravado, and wars the author thinks are characteristic he is saying that these things have both propelled Japan forward - i.e. led to economic development and political influence etc, and set it back, i.e. in some way prevented Japan from developing in some other, unspecified way. It's a little bit cryptic, as he doesn't specify how exactly these things have helped Japan to both develop and be prevented from developing, although maybe he enlarges on that elsewhere in the book.