South Korean President Park Geun-hye said on Monday an anti-North Korea law was needed because the two countries remained technically at war, after a Korean-American was deported to the United States under the law for making positive comments about the North.
However, Park also said she remained open to a summit meeting with the North's leader Kim Jong Un to ease tensions.
Shin Eun-mi, a South Korea-born American who came to the South last year as a tourist, has spoken positively of life in North Korea in speeches around the country, as well as in online posts. She also blamed South Korea's news media for encouraging alienation between the people of the two sides.
"Not all countries face exactly the same circumstances," Park said at a news conference, when asked about the National Security Law, the anti-North statute which Shin is accused of violating.
"We need the very minimum of law to ensure security in this country as we remain in a standoff with the North, and the law is enforced according to that," she said.
Earlier on Monday, a Justice Ministry official confirmed Shin had been deported for violating the National Security Law as well as the immigration control law.
"She was taken to the (airport) and was expelled, and is barred from re-entry for the next five years," the ministry official said asking not to be named.
The National Security Law, enacted after the two Koreas were split at the end of World War Two but before the 1950-53 Korean War, prohibits South Koreans from publicly praising the North Korean regime. The war was ended only by a truce and not a peace treaty.
The law is considered obsolete mostly by liberal critics, who say it is used by conservative governments to stifle political opposition and suppress freedom of speech.
Shin boarded a plane on Saturday. Yonhap news agency said she landed in Los Angeles on Saturday local time and a scuffle broke out at the airport between supporters welcoming her back and opponents.
Appearing before reporters on Saturday after questioning by immigration authorities, Shin said she was being deported "but my love for my homeland cannot be expelled".
"I will be wishing peace and unification for my homeland from afar with the love I have for my compatriots," she said.