Former Japanese Prime Minister Junichiro Koizumi has been actively advocating for denuclearization in North Korea. Not new to such efforts, Koizumi took the lead in negotiations with the estranged nation during his tenure as Prime Minister. While it's uncertain when he began this renewed push, it indicates a continuing concern over nuclear threats from North Korea in Japan's political landscape.

Japan has persistently been concerned about North Korea's nuclear program due to its proximity and historical tensions. Denuclearization is perceived as a sure way to promote peace and stability in the region, a sentiment widely held among the Japanese populace. It also aligns with Japan's post-WWII pacifist constitution and its stand against nuclear weaponry.

In the US or EU, diplomacy with North Korea also focuses on denuclearization. However, their strategies can differ widely based on their specific national interests and global roles. In general, these Western nations tend to leverage sanctions or diplomatic negotiations but can also display a willingness to adopt a more confrontational approach if necessary.