TOKYO—Honda and Nissan on Thursday officially scrapped their planned merger less than two months after announcing it, putting pressure on troubled Nissan to look for other partnerships.The two Japanese automakers had said in December that they planned to combine operations by 2026,

Japanese automakers Honda, Nissan and Mitsubishi said Thursday they are ending talks on business integration. Nissan Chief Executive Makoto Uchida said the talks had changed focus from setting up a joint holding company to making Nissan into a subsidiary of Honda.

The Japanese companies’ decision to call off negotiations highlights the challenges legacy automakers face in partnering to tackle new technologies.