Four years have passed since Seoul slapped blanket economic sanctions on North Korea in May 2010 in retaliation for its torpedo attack on a South Korean warship that killed 46 sailors. The measure imposed by the conservative government of then-President Lee Myung-bak was taken over by the incumbent administration of his successor Park Geun-hye, who took office in February last year.

Park’s adherence to the punitive policy disappointed Pyongyang, which might have expected her to discard it to build confidence between the two Koreas. She made no mention of relaxing Seoul’s extensive sanctions in a speech given during a visit to Germany in March to outline her vision for laying the groundwork for national reunification.

A string of provocative acts by North Korea, coupled with its refusal to admit to and apologize for the deadly attack, have given little room for Park’s administration to consider lifting or easing the ban on bilateral trade and new investment in the North. From the opposite viewpoint taken by some experts here, Pyongyang’s attempts at increasing tension on the peninsula, with some interludes of peace overtures, may be intended to push Seoul to withdraw the sanctions.

Its recent behavior, seemingly confusing and contradictory, may be better understood in this vein. A week ago, North Korea fired artillery shells within a short distance of a South Korean naval vessel on patrol south of the disputed maritime border in the West Sea. On the following day, it flatly denied the shelling and announced it would participate in the 2014 Asian Games to be held in the South this fall. Earlier last week, North Korea allowed Cardinal Andrew Yeom Soo-jung to visit the border city of Gaeseong to meet Catholic workers in the factories run by South Korean companies there a day after its fishing and patrol boats violated the sea border.

This pattern of acts appears carefully calculated to fuel disputes between Park’s conservative administration and liberal groups over how to deal with Pyongyang and, in particular, add weight to calls for lifting the ban on inter-Korean trade and investment projects except for the Gaeseong industrial park. The announcement of the North’s participation in the Asian Games came just a day before the sweeping sanctions on the communist regime reached the four-year mark.

In a recent survey of North Korea watchers here, about 90 percent of the 113 respondents agreed that either lifting or easing the measure would help expand inter-Korean economic ties and reduce tensions on the peninsula. More than half of them said the sanctions caused more losses to the South than the North.

Lifting the sanctions unconditionally would damage the principle of getting North Korea to make due payment for its serious provocations. More fundamentally, Pyongyang’s refusal to give up its nuclear weapons program is limiting Seoul’s options for full-fledged economic cooperation between the two sides.

But it is also true that the stringent stance on the North has brought about few changes in the recalcitrant regime’s attitude, blocking any possible route to a breakthrough in inter-Korean relations. In this sense, Seoul officials may need to think more flexibly about ways to apply sanctions on North Korea.

There may be measures that could draw a response from Pyongyang, such as a substantial increase in assistance aimed at improving the living conditions of North Koreans, without filling the coffers of its ruling class. It will be up to Park’s new national security team, to be formed following the recent resignation of two key aides, to map out this more sophisticated strategy for handling the North.