Whoever wins South Korea's presidential election on Tuesday will have no honeymoon period.
The winner will have to take office immediately and confront, among other issues, a host of national security challenges which have dominated the campaign.
Yonsei University's political science professor Rhyu Sang Young said that national security has become an important issue due to the "critical timing" of the election, which comes amid escalated tensions on the Korean peninsula.
The hasty deployment of an advanced United States missile shield to deal with missile threats from the North has deepened a row between South Korea and its powerful neighbour China.
China's economic retaliation over the Thaad (Terminal High Altitude Area Defence) system has hit South Korea's tourism, entertainment and beauty sectors, dealing a blow to its economy.
"We have a power vacuum now and things have been very unstable. People are very concerned about security and the Thaad issue. There's a heightened sense of insecurity here," noted Prof Rhyu.
Polling Day was brought forward by the March impeachment of former president Park Geun Hye over a massive corruption scandal.
For voters, the issue is exacerbated by a widely expected power shift from a pro-US conservative government that is tough on the North to a liberal one that is Pyongyang-friendly, which some fear may strain the US-South Korea security alliance.
Front runner Moon Jae In from the liberal Democratic Party, for one, drew flak for refusing to label the North as South Korea's "main enemy" in a TV debate, fuelling suspicion that he could be too soft on Pyongyang if elected.
His main rival Ahn Cheol Soo from the centre-left People's Party, meanwhile, has been accused of lacking principles on national security for reversing his position to support the deployment of Thaad in South Korea.
There are also worries that South Korea is being sidelined in negotiations by the US and China to deal with the belligerent North.
US President Donald Trump, in an interview with Reuters last week, said he wanted Seoul to foot the missile shield's US$1 billion (S$1.4 billion) bill. He also pushed for the five-year-old US-South Korea free trade deal - which he calls "horrible" and "unacceptable" - to be renegotiated. His remarks have raised questions about his commitment to the bilateral alliance.
Experts say the new administration will face huge hurdles trying to reset ties with North Korea, the US, China and Japan.
US scholars have warned that a Moon presidency could be problematic for the US, especially as the former human rights lawyer and key aide to late progressive president Roh Moo Hyun appears to be pushing for less dependence on the US and leaning towards China.
But in a recent interview with The Washington Post, Mr Moon said he is "on the same page" as Mr Trump. "Trump talks about strenuous pressure, sanctions and even the possibility of a pre-emptive strike, but I believe his ultimate goal is to bring North Korea back to negotiations for the nuclear programme. In that respect, I share the same opinion as President Trump," he said.
Mr Moon's adviser, Yonsei University professor Kim Ki Jung, said Mr Moon views North Korea as a market that can "provide vitality to the South Korean economy". "We basically think that the benefits of economic ties will override the security crisis, and we can also use it as leverage to move North Korea (to the negotiation table)," said Prof Kim.