The think-tank was established in 2008 by NATO members, on the initiative of Estonia, in response to the country suffering crippling cyberattacks allegedly committed by Russia.
With the addition of the three new member nations, CCDCOE now has a total of 32 members -- 27 sponsoring members of NATO and five contributing participants, including South Korea, that are not part of NATO.
South Korea's NIS said it has been working to become a member of CCDCOE since 2019 to gain cyberattack response expertise in order to protect the country's backbone infrastructure, and to formulate a global strategy.
The intelligence agency said it plans to send more staff to the centre and expand the scope of joint training.
Cyber threats were causing enormous damage to individuals and countries which require close global cooperation to respond to, NIS noted, adding that it will work closely with CCDCOE members going forward.
Even prior to becoming an official member of the centre, South Korea had taken part in CCDCOE's large-scale, live-fire cyber defense exercise, Locked Shields, where thousands of experts from member nations and partners jointly defended a fictional country against simulated cyberattacks.