Prime Minister Takaichi Sanae’s Liberal Democratic Party (LDP) won a landslide victory in the general election on February 8, 2026, winning 316 seats on its own. Together with the Japan Innovation Party, with whom the LDP has a non-cabinet alliance, the governing coalition now holds 352 seats, or 75.7 percent of the total seats in the House of Representatives (465 seats), giving it well over a two-thirds majority. The two parties aim to amend the Constitution and bolster Japanese defense capabilities and intelligence functions through a coalition agreement. Will Japan now simply forge ahead with strengthening its military capabilities by suddenly amending the Constitution?

While Japan does indeed appear set to upgrade its defense capabilities, amending the Constitution is unlikely to proceed as easily. There are three key domestic political factors at play.

First, a procedural factor. Since Japan’s governing structure uses a bicameral system, motions for constitutional amendments must be submitted in both houses. In practice, however, there is a major hurdle. Although LDP has the necessary two-thirds majority in the House of Representatives, or Lower House, after its landslide win in February, it falls short in the House of Councillors, the Upper House, even when taken together with the Japan Innovation Party. Since the prime minister cannot dissolve the House of Councillors, which had its election in July 2025, this distribution of power in the Diet will not change until the next House of Councillors election in 2028. Moreover, just because the House of Councillors does not put forward a motion, that does not mean that the will of the House of Representatives may be regarded as the will of the Diet.

Regarding the bicameral system, while the Act on Procedures for Amendment of the Constitution of Japan was enacted in 2007 as a procedure for a constitutional amendment, the details have not yet been fully defined.  It is also unclear whether it will be possible to propose and vote on multiple amendments as a package, as was the case with the approval of same-sex marriage in Article 24 and the amendment of the peace clause in Article 9. There is no guarantee that the relevant laws and regulations that may be necessary will be safely enacted in the House of Councillors.

Second, a practical reason. Even in the House of Representatives, where the LDP and the Japan Innovation Party have secured an overwhelming majority, there exists no amendment bill that can currently win the approval of more than two-thirds of the house’s members when it comes down to the details about which parts of the Constitution to amend in the first place. It is true that only three parties, the Japanese Communist Party, the Social Democratic Party, and the Reiwa Shinsengumi, are opposed to a constitutional amendment outright, so a motion being blocked by one-third of the seats is unrealistic. As such, at first glance an amendment seems likely to pass.

It is doubtful, however, whether a consensus can be reached among parties that are not necessarily against an amendment per se. Regarding Article 9 of the Constitution, opinions range from advocating an abolition of the peace clause and the creation of national armed forces to those arguing that it is sufficient to add a clause about the Self-Defense Forces to the current article text. There is also a wide spectrum of other opinions as well, such as about explicitly naming the emperor are head of state, specifying environmental rights, specifying same-sex marriage, abolishing or drastically downsizing the House of Councillors, and expanding local autonomy. Many also argue that making amendments should be made easier by amending the provisions of Article 98. There is no consensus on these points among those seeking amendment.

This makes it clear why it is not safe to assume that the LDP’s landslide victory will automatically lead to constitutional amendment. Nonetheless, this also does not mean that Japanese security policy will not change.

Third, the two-tier legal structure. Even if the conventional framework remains unchanged at the constitutional level, there will be a major shift toward strengthening defense capabilities at the sub-levels of laws and budgets. It is likely that the defense budget will be increased to boost the collective security system as the alliance with the United States strengthens, while work on developing the capability to attack enemy bases may also begin in earnest. Expanding intelligence functions and enacting anti-espionage legislation are already part of the coalition agreement, with movements being made immediately after the general election. There is no doubt that Takaichi’s drive for conservative policy will intensify in areas where accommodations can be made by way of laws and budgets.

The constitutional order will undoubtedly be transformed in such a way that defense capabilities are strengthened. In that case, since the current constitution looks unlikely to be amended, it will be difficult to make changes that go beyond a general framework of strengthening defense capabilities and that would allow Japan to pose a threat to neighboring countries.