The talks on management integration between Honda Motor Co. and Nissan Motor Co. ended after only six weeks. This collapse of a major restructuring plan, which was expected to boost competitiveness, is deeply disappointing. Both companies must act quickly to protect Japan's core automotive industry.

The breakdown occurred after Honda proposed making Nissan a subsidiary. Initially, the plan called for an "equal partnership" under a holding company. However, Honda, concerned about Nissan's management reconstruction, shifted its approach to take the lead in restructuring. Nissan rejected the proposal, unwilling to lose its autonomy.

The auto industry is undergoing a seismic shift, with massive investments required for electric vehicles (EVs) and autonomous driving technology. For companies trying to go it alone, survival looks increasingly difficult. This was precisely why Honda and Nissan entered merger discussions.

Nissan, in particular, is in a dire situation. Its sales have dropped by more than 30% over the past five years, and it expects a final deficit of 80 billion yen (approximately $525 million) for this fiscal year. While the company has taken steps including closing overseas plants, it has yet to present a clear recovery plan.

The merger could have provided major benefits, including giving Nissan access to Honda's hybrid vehicle technology -- a known weak spot for Nissan. Without offering an alternative strategy, Nissan risks failing its shareholders, employees and business partners.

At the same time, it is also difficult to say that Honda presented a convincing strategy of how the merger would create synergy. To promote the standardization of key components and the differentiation of vehicle models, both companies needed a vision to further pursue their strengths and complement each other to cover their weaknesses. Yet, during the Dec. 23 press conference announcing the merger talks, Honda President Toshihiro Mibe struggled to answer when asked, "What do you admire about Nissan?"

Both companies have said they will maintain their EV partnership established last summer, but rebuilding trust will be a steep challenge.

Going forward, cross-industry restructuring is likely to increase. For example, Taiwanese electronics giant Foxconn, officially known as Hon Hai Precision Industry Co., has expressed interest in deepening its ties with Nissan. Mergers and partnerships have significant implications for employment and regional economies. Japanese firms must carefully evaluate these impacts.

With the EV market slowing and protectionism rising, uncertainty continues to grow. What is needed now is the ability to navigate these turbulent times. There is no room for repeated missteps.