South Korea is starting production for its new cutting-edge stealth jet known as the KFX.

The design for the KFX, which stands for Korean Fighter Experimental, is the result of almost two decades of planning that cost the government approximately 8.6 trillion won ($7 billion).

Once production begins on 120 units of the new jet, local media reports that an additional 10 trillion won will be needed, putting the bill for the entire project at around 18.6 trillion won.

The Defense Acquisition Program Administration (DAPA), South Korea’s arms procurement agency, concluded its three-day critical review of the jet’s design last week, giving its final approval on Friday.

Production of a prototype model begins this month.

According to Ryu Kwang-soo, head business manager of the KFX project at Korea Aerospace Industries (KAI) – the project’s main developer, around 9,300 out of the approximately 12,000 detailed blueprints needed for the KFX project are complete – 78 percent of the project, including key components.

As a major national project, development for the KFX was led by the government’s Agency for Defense Development (ADD) and KAI, but approximately 225 private firms also partook in the process, including all of the country’s major defense contractors. Foreign stakeholders in the project include Indonesian Aerospace and the U.S. company Lockheed Martin, which provided technical assistance and several pieces of technology integral to the jet’s development.