SEOUL - South Korean residents and civic group activists filed a petition on Thursday against the deployment of the US Terminal High Altitude Area Defense missile defense system, which they claim is unconstitutional.

Residents from Seongju county and Gimcheon city and peace activists gathered outside the constitutional court in Seoul, holding a news conference before submitting the appeal.

According to the petition document, the residents and activists said the THAAD deployment violated many of the Constitution clauses while failing to follow any appropriate procedures.

Seoul and Washington abruptly announced a decision in July to install one THAAD battery in the country by the end of this year. Just three days before the announcement, Defense Minister Han Min-koo told lawmakers that he hadn't been informed of any notice about the THAAD installation.

Foreign Minister Yun Byung-se visited a department store when the THAAD deployment decision was announced, indicating no advance discussions between ministers of defense and foreign affairs and the presidential office.

The petitioners said the decision-making process on THAAD was rough and ready as there was no approval in the Cabinet meeting, and that it was unilaterally determined by the national security council of the presidential office.

"The THAAD decision did not follow any proper procedure. No effort has been made for dialogue with residents," said Ha Joo-hee, an attorney at Lawyers for a Democratic Society, an advocacy group composed of liberal lawyers.

He said such an important decision that could influence the fate of the whole nation must be properly disclosed beforehand to the public and Parliament.

The petitioners claimed the US missile shield deployment in their territory is unconstitutional as it violates rights to peaceful life, health and environment, which the country's constitution guarantees.