South Korea has tightened the screw on North Korea by slapping tougher unilateral sanctions over the North's recent nuclear and missile tests, adding to its punitive actions taken in 2010 in response to the North's attacks.

On May 24, 2010, Seoul slapped comprehensive sanctions on North Korea to punish it for the torpedoing of the South Korean warship Cheonan two months earlier.

The 2010 punitive measures excluded operations at the joint industrial park in North Korea's border city of Kaesong and Seoul's humanitarian assistance.

But the North's nuclear and missile provocations have altered Seoul's calculation of dealing with the North, experts here said.

On Feb. 10, South Korea shut down the Kaesong Industrial Complex in response to North Korea's fourth nuclear test in January and long-range rocket launch the following month, ending the last symbol of inter-Korean reconciliation.

In March, Seoul announced its fresh unilateral sanctions against Pyongyang, including blacklisting North Koreans and entities suspected of being involved in the North's nuke and missile program.

The move was designed to lend support to the United Nations Security Council's tougher sanctions on Pyongyang imposed in early March.

"The May 24 sanctions have been in place as North Korea has not apologized for its attack on the warship," Moon Sang-gyun, a spokesman at Seoul's defense ministry, told a regular press briefing Monday. "At a time when North Korea calls itself a nuclear state, now is the time to maintain sanctions and put pressure on Pyongyang."

Under the 2010 punitive measures, Seoul banned North Korean-flagged vessels from entering the South's ports and prevented its nationals from going to the North except for visits to the Kaesong factory zone and Mount Kumgang in the North.

But a year later, Seoul relaxed some of its sanctions, apparently mindful of concerns that the prolongation of the measures would hamper inter-Korean reconciliation.

In May last year, the government said that it will encourage more civic groups to spur exchanges with North Korea in such nonpolitical areas as sports and cultural programs to mark the 70th anniversary of Korea's liberation from Japan's 1910-45 colonial rule.

South and North Korea's Aug. 25 deal on easing military tension also helped long-strained inter-Korean ties enjoy a short-lived rapprochement last year.

The two sides held reunions of families separated by the 1950-53 Korean War in October at a facility on Mount Kumgang, which was once the main venue for a joint tourism program.

But North Korea's nuclear and missile tests early this year prompted Seoul to tighten the screw on the North this year.

Since the North's latest nuclear provocation, South Korea has suspended almost all inter-Korean civilian exchanges and is not allowing South Koreans to visit North Korea.

Seoul has also taken the toughest nonmilitary actions by shutting down the joint factory complex, whose operations continued even when North Korea staged two deadly attacks in 2010. Besides sinking the warship, the North shelled Yeonpyeong Island.

South Korea, meanwhile, has called on North Korea to show its commitment to denuclearization before Pyongyang talks about dialogue with Seoul.

North Korean leader Kim Jong-un proposed to hold military talks with the South at the congress of the ruling Workers' Party of Korea, which concluded its four-day run on May 9.

Last week, the North also offered to have a working-level meeting in late May or early June to prepare for inter-Korean military talks. Seoul has rejected Pyongyang's offer as a propaganda ploy without sincerity.

"The North's dialogue offer appears to be aimed at driving a wedge between people living in the South and at weakening the international sanctions regime," Jeong Joon-hee, spokesman at Seoul's unification ministry, said at a regular press briefing.

"Now is not the time to talk about inter-Korean dialogue."

Some experts said that the government should also open the door for negotiations with Pyongyang behind the scenes while putting pressure on the North.

"If Seoul only sticks to sanctions and pressure on the North, there will be high risks for inter-Korean ties," said Yang Moo-jin, a professor at the University of North Korean Studies. (Yonhap)