Toyota Motor (7203.T) will restart operations at its assembly plants in Japan on Wednesday after a production system malfunction brought domestic output to a halt at the world’s biggest-selling automaker. The company said it would restart production at 25 of the 14 factories affected by Tuesday’s halt in the morning, adding two plants in the afternoon. Toyota halted output after its supplier Kojima Industries Corp discovered a computer error and found a message on one of its servers that said it was the victim of a cyberattack.

The firm is a pioneer of just-in-time inventory management, which keeps costs low but means supply chain snarls can dent output. Toyota’s Japan output averaged about 13,500 vehicles daily in the first half, excluding group automakers Daihatsu and Hino. Its production rebounded after a series of cuts blamed on semiconductor shortages last year.

Toyota’s production was halted because the supplier’s systems were affected, and it couldn’t place orders for parts, Kojima said in a statement. It needed to be clarified what caused the error, and the company said it would keep a close eye on its systems.

Japan’s top government spokesman, Hirokazu Matsuno, said the problem at Kojima was likely caused by a hacking attack and urged companies to boost their cybersecurity. He spoke after Japan joined Western allies in clamping down on Russia over its invasion of Ukraine.

The firm said the problem at Kojima was limited to one of its file servers. Its other servers were not affected, and it continued to operate normally. It said the company had hired security experts to investigate what caused the problem.

Toyota also said it was still assessing the damage to its plants in northeastern Japan and Tokyo, which were hit by strong earthquakes earlier this month that caused widespread power outages and flooded roads.

Among its other moves, Toyota said it would partially resume operations at a plant in Southeast Asia that is delayed in procuring some components from its suppliers because of flooding. It said it will maintain its planned global production volume for the fiscal year that ends next March.

Toyota’s production snarls were exacerbated by ongoing power outages in Japan’s capital and fuel shortages that have disrupted transportation. Other Japanese firms are grappling with damaged plants and suppliers in the quake-hit region, a lingering nuclear crisis, and a military coup in Myanmar that has sparked fears of instability. Japan’s companies have been recovering after the 2011 earthquake and tsunami, but disruptions from the recent disasters and political turmoil are hitting output, sales, and investment. The nation’s stock market has fallen sharply this year. Its benchmark Nikkei 225 index lost nearly 15% in the year’s first half. That has sparked concern that the economy is losing steam and depressing corporate earnings. Companies have been reluctant to raise full-year profit forecasts for fear of a slowdown in the world economy and volatile currency markets.