Nippon Steel Kenjiho Steelworks (Songnim)

The Nippon Steel Kenjiho Steelworks (日本製鐵兼二浦製鐵所) was one of the largest integrated iron and steel production facilities in colonial Korea. Located in Kenjiho (兼二浦, also romanized as Kyŏmip'o), in Hwanghae Province — present-day Songnim City, North Hwanghae Province, North Korea — the plant was a cornerstone of Japan's wartime heavy industrial base on the Korean peninsula.

Construction began in 1915 under Mitsubishi Gōshi Kaisha and was taken over in 1917 by the newly founded Mitsubishi Steel Company (三菱製鐵), with the first blast furnace ignited on June 13, 1918. The site was chosen for its access to local iron ore deposits, coal from nearby mines, and river and coastal transport via the Taedong River estuary. By the early 1920s, the facility had steel and rolling capabilities, though steelmaking and rolling were suspended from April 1922 in the wake of post-WWI naval arms reduction, leaving only the blast furnaces in operation until around the 1934 merger.

In 1934, following the Japanese government's policy of consolidating the steel industry, Mitsubishi Steel merged into the newly formed Japan Iron & Steel Co., Ltd. (日本製鐵株式會社), and the plant became the Kenjiho Works. Production was progressively expanded through the mid-1930s. At peak capacity, the facility operated three blast furnaces (annual capacity: 350,000 tons of pig iron), four coke oven batteries (379,000 tons), three open-hearth furnaces (150,000 tons of steel ingots), and rolling mills producing 70,000 tons of structural steel and 100,000 tons of thick plate annually.

During World War II, the Kenjiho Works was a critical supplier for Japan's military-industrial complex. Its primary outputs were large structural steel sections and shipbuilding-grade thick plate. The plant also produced approximately 30,000 tons per year of specialty low-phosphorus pig iron, which was shipped primarily to the Kure Naval Arsenal for use in warship construction. The workforce at the end of 1942 comprised approximately 82% Korean and 18% Japanese workers.

On August 27, 1945, two weeks after Japan's surrender, all blast furnaces were blown down and Japanese operations officially ended. In February 1946, the facility was renamed the Hwanghae Iron Works (黄海製鉄所) under Korean management. With post-war Soviet and Chinese assistance, it was rebuilt and expanded as the Hwanghae Iron and Steel Complex, which continues to operate today as one of North Korea's principal steel production facilities.