The daughter of the late dictator and vehement anti-communist Park Chung-Hee, Park campaigned on a policy of cautious engagement with Pyongyang in contrast to her hawkish predecessor, Lee Myung-Bak.
But her plans are likely to be shelved, at least for the short term, after the February 12 nuclear test angered the public in the South and emboldened hawks in Park's ruling conservative party.
The UN Security Council is still debating how to respond, but is almost certain to toughen sanctions on Pyongyang -- a move that could trigger a sharp response from the North and possibly even another nuclear test.
Kim Jang-Soo, a former defence minister who has been appointed Park's national security adviser, signalled on the same day as the test that the new administration's policy could "not be the same as before".
Park strongly condemned the test and warned the regime of North Korean leader Kim Jong-Un that it would bring about its own collapse with its complete isolation from the international community.
Park's first challenge will be hardliners in her own party who are staunchly opposed to engaging Pyongyang and some of whom have even begun calling in public for South Korea to build its own nuclear deterrent.
"We urgently need to solve the unbalanced nuclear capability between the two Koreas and may need nuclear arms ourselves for minimum self-defence," said Won Yoo-Chul, a senior member of Park's New Frontier Party.
A survey by Gallup Korea published on Wednesday showed more than 60 percent of South Koreans support the idea of Seoul having its own nuclear weapons capability.
At the same time, Park's efforts to mollify her party hawks are being undermined by the increasingly bellicose statements coming from the North.
On Tuesday, the North Korean envoy at the UN Conference on Disarmament in Geneva warned that South Korea faced "final destruction" if Seoul and its allies pushed for tougher UN resolutions over the North's nuclear program.
Kim Yong-Hyun, a professor of North Korea studies at Dongguk University, said Park's hands would be tied after she took office.
"The UN Security Council will surely impose more sanctions that will be supported by Seoul," Kim said. "In that climate, I see little possibility for substantial cross-border talks for six months at least."
Park had promised a package of substantial welfare programs aimed at the South's rapidly growing elderly population, but the North's test has already resulted in a shift in spending priorities.
"We are now faced with an unexpected need to increase the defence budget," Park said Monday.
The North has traditionally sought to test the mettle of the South's new leaders as they take office, sometimes with a view to forcing Seoul -- and the United States -- into negotiations.
Despite the difficult environment, Moon Chung-In, a politics professor at Yonsei University, said Park needed to move swiftly and "proactively" to position South Korea as the chief international mediator with the North.
"That way Park will enjoy more diplomatic leverage with China and the US than before... so she needs to take a more open and proactive stance," Moon said.
Inter-Korean contacts have been effectively frozen since Seoul accused Pyongyang of torpedoing one of its warships in March 2010, and halted almost all trade and aid to the impoverished North.
The North denied involvement, but went on to shell an island on the South Korean side of their disputed maritime border in November 2010, leaving four South Koreans dead and sparking brief fears of a full-scale conflict.
Paik Hak-Soon, a North Korean analyst at the Sejong Institute think tank, said the hardline stance of Park's predecessor, president Lee, had failed to produce any results and should be discarded.
"If Park takes a confrontational stance, she will end up repeating the same mistake as Lee, who not only failed to curb the North's nuclear ambitions, but also saw inter-Korea relations worsen," Paik said.
"She needs to act as soon as possible to restart a dialogue, though it won't be politically easy," he said.