North Korea's flurry of ballistic missile launches has prompted the government to move up plans to deploy a land-based Aegis missile defense system.

Government sources said 2.1 billion yen ($18.7 million) would be earmarked in a supplementary budget to meet contractual costs with the United States for the Aegis Ashore defense system within the current fiscal year, which ends March 31.

Cabinet approval is expected as early as Dec. 22.

Initially, the government had planned to set aside funding for the Aegis Ashore system in the ordinary budget for fiscal 2018 with the aim of full deployment within fiscal 2023.

However, a high-ranking Defense Ministry official said that repeated missile provocations by North Korea had sparked calls to begin studies into the system earlier so that operations can start before fiscal 2023.

A portion of the funds to be included in the supplementary budget will cover the cost of bringing U.S. engineers to Japan to help select sites for the Aegis Ashore system. The engineers will be asked to assist in tests about possible radio wave disturbance at the Ground Self-Defense Force training areas in Akita city and Hagi, Yamaguchi Prefecture, that are being considered as possible deployment sites.

The government still plans to ask for additional funds in the fiscal 2018 ordinary budget for the Aegis Ashore system.