The government plans to upgrade all eight of its Aegis destroyers by fiscal 2027 so that they can install Tomahawk cruise missiles purchased from the United States, a government source said Saturday.

The move is intended to help Japan develop capabilities that can strike targets inside an adversary's territory, amid North Korea's growing nuclear and missile threats and China's military rise.

According to the source, Japan plans to acquire the latest Tomahawk Block-5 missiles with a range of about 1,600 kilometers. The government has already announced a plan to purchase 400 Tomahawks, earmarking ¥211.3 billion ($1.6 billion) in the budget for fiscal 2023 starting April.

Currently, two Maritime Self-Defense Force ships equipped with the Aegis missile defense system are stationed at the Yokosuka naval base in Kanagawa Prefecture. Two others are based at Maizuru base in Kyoto Prefecture and the remaining four at the Sasebo base in Nagasaki Prefecture.

The government plans to earmark funds to refurbish the vertical launching system of each ship from fiscal 2024 for the installation of Tomahawk missiles.

Japan also plans to add two more Aegis ships by fiscal 2032 and commission two vessels by fiscal 2028 that will be built as an alternative to a scrapped plan to deploy a land-based Aegis missile defense system.

Late last year, Japan decided to acquire so-called counterstrike capabilities and double its defense spending in a dramatic shift in its postwar security policy under the nation's war-renouncing Constitution.

The Japanese government has maintained that having the capability to strike enemy bases is possible under the Constitution if it can be considered a measure of self-defense. But Japan had until now not opted to equip its Self-Defense Forces with the abilities, leaving the role up to its security ally, the United States.