Defense Minister Taro Kono said Tuesday that Japan will pursue discussions with the United States over their 180 billion yen ($1.7 billion) contract to deploy Aegis Ashore land-based missile defense batteries in Japan, a day after he suspended the plan.

The price of the deal to introduce two units of the U.S.-developed system designed to counter the North Korean ballistic missile threat includes 12 billion yen already paid by Japan, Kono told a parliament session.

The minister abruptly announced the suspension of the deployment plan on Monday, citing technical problems and ballooning costs.

Prime Minister Shinzo Abe, who had fervently pushed for the Aegis Ashore deployment, said there should be no "vacuum" created in shielding the country from ballistic missile threats, but the existing plan could not proceed.

"We cannot move it forward anymore now that it's become clear that the very premise we used when explaining to local people (in the areas that would host the systems) is different," Abe told reporters at his office, in his first public remarks since the suspension was announced.

The Aegis Ashore system, which was meant to supplement the Maritime Self-Defense Force's Aegis-equipped destroyers, was expected to go into operation in fiscal 2025 at the earliest, with one candidate site in the northeastern prefecture of Akita and the other in the western prefecture of Yamaguchi.

Asked in a press conference whether he had considered selecting other areas as host sites, Kono denied it, saying, "This investment should not be made."

"Our understanding of the matter was naive," he added.

Earlier in the day, Kono told the House of Representatives Security Committee that the Japanese government decision in December 2017 to deploy two batteries of the Aegis Ashore system was "correct at the time," but it "cannot be deemed rational given the cost and time" required to prepare for its operation.

The plan was unpopular with local residents concerned about the health effects of electromagnetic waves emitted by Aegis Ashore's radar, as well as the possibility of their communities being targeted in an armed conflict.

"We've been troubling the local people, so I have to apologize to them," Kono said.

On Monday, Kono said it would be difficult to ensure that the rocket booster of an interceptor missile would land in a Self-Defense Forces training area or the sea, as promised by the Defense Ministry since August 2018, without hardware modifications.

Referring to the cost and the more than 10 years spent on improving the Standard Missile-3 Block IIA interceptor, an anti-ballistic missile jointly developed by the United States and Japan, Kono said "similar costs and time" would be required to resolve the technical issue of the Aegis system.

Abe's Cabinet may approve the policy change on the Aegis Ashore system after the government's National Security Council discusses the matter, Kono added.

Foreign Minister Toshimitsu Motegi denied during the parliamentary session that Tokyo's decision to suspend the Aegis Ashore deployment would negatively affect "various cooperation" with Washington, while an opposition lawmaker criticized the Defense Ministry for making the judgment "too late."

The planned Aegis Ashore deployment in Japan reflects U.S. President Donald Trump's push to sell more military equipment under his "Buy American" policy.

In a briefing session by Defense Ministry officials to the ruling Liberal Democratic Party, Itsunori Onodera, who was defense minister in 2017 when the government decided to deploy the system, said, "I cannot accept it without a detailed explanation."

Shigeru Ishiba, another former defense minister, told reporters after the briefing that he thinks halting the introduction of the Aegis Ashore system would "create a hole" in Japan's defense capability.

"We had never expected it," Akita Gov. Norihisa Satake told reporters Tuesday on the abrupt suspension of the Aegis Ashore deployment plan, demanding Kono offer an apology to local residents for causing "unnecessary anxiety."

Satake added he got the impression that the plan had been "completely withdrawn" rather than halted when he spoke with Kono over the phone.

The Defense Ministry was found to have conducted an erroneous geographical survey in selecting Akita's Araya district as a candidate site for an Aegis Ashore battery.

Faced with criticism, the government decided to redo geographical assessments at 20 potential sites in the northeastern region of Tohoku, including Araya, while the Yamaguchi site remained a candidate to host one of the units.

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