These are euphoric but anxious days for South Korea, as the heady impeachment of a deeply unpopular president leaves the country without a recognised leader at a time of military tensions with nuclear-armed North Korea.

And with Pyongyang smarting from a fresh round of UN sanctions and never shy about embarking on a dangerous game of brinkmanship, the one thing the country doesn't want to display is vulnerability.

But so considerable are the powers vested in the executive in South Korea that Friday's impeachment stripping them away from President Park Geun-Hye inevitably leaves a sizeable vacuum that must seem all too tempting to provocateurs in Pyongyang.

It's a concern that was swiftly addressed by Prime Minister Hwang Kyo-Ahn, the unelected former prosecutor who has temporarily taken on the role and authority of acting president.

At an emergency cabinet meeting on Saturday, Hwang said he had instructed the military to be extra vigilant to any move by the North to exploit the current situation.

"The government is carrying out all measures necessary to prevent any government vacuum and ease the people's anxiety," Hwang said.

"Up until now ... no special development from North Korea has been reported. But all civil servants should work with a sense of tension for the time being," he added.

- 'Vegetable president' -

North Korean state media, which has issued highly personal attacks on Park in the past, has clearly enjoyed witnessing her downfall and the attendant political chaos.

On Saturday, the ruling Workers' Party newspaper Rodong Sinmun called the impeached Park a "vegetable president", and said her continued refusal to resign was the act of "an old witch and psychopath without equal".

But is ridicule likely to lead to provocation?

Most analysts believe the North will resist the temptation and adopt a wait-and-see strategy -- not only towards the situation in the South, but also towards Washington and the incoming administration of US president-elect Donald Trump.

North Korea has a tendency to try and test new US presidents, but Trump is such an unknown quantity -- especially on foreign policy -- that it might choose to hold off for a while.

"It'll want to spend time feeling out the policy directions of the Trump administration," said Yang Moo-Jin, a professor at the University of North Korean Studies in Seoul.

"In the meantime, it's unlikely to stage a fresh nuclear test which might set Trump on a hardline course early on," Yang said.

- Enough test data -

North Korea has conducted two nuclear tests already this year, and multiple missile launches in its push for a weapon capable of delivering a nuclear warhead to the US mainland.

"North Korea's weapons testing timeline is primarily driven by its ambitions to increase military capabilities, and the recent tests give its scientists and engineers much technical data to work with," said Leif-Eric Easley, a research fellow at the Asan Institute for Policy Studies in Seoul.

"So Pyongyang may wait to see if a pro-engagement politician emerges from South Korea's political tumult," Easley said.

Park took a hard line with Pyongyang throughout her presidency, refusing to offer any concessions unless the North made a tangible commitment to denuclearisation.

In a shock move, she even closed down the Kaesong joint industrial zone -- a rare North-South cooperative project that had survived previous cross-border crises.

North Korean leader Kim Jong-Un "knows exactly what he is doing," said Koh Yu-Hwan, a political science Professor at Dongguk University.

"There is no reason for him to stage provocative acts and change the atmosphere in the South in favour of conservatives," Koh said.

The North is also preparing for a series of key anniversaries, including the 75th and 105th birthdays of late leaders Kim Jong-Il and Kim Il-Sung in February and April respectively, as well as the 85th anniversary of the army's founding on April 25.

In the past, such dates have been marked by strategic weapons' tests, but Yang predicted that Pyongyang would avoid being overly confrontational.

"I think the festive mood will favour stability over disturbance," he said.

- How long? -

The problem is that the political uncertainty in South Korea could carry on for much longer than Pyongyang is willing to wait.

Park's impeachment has to be approved by the Constitutional Court -- a process that could take six months. If it confirms her ouster then a presidential election must be held, but that could take another 60 days.

"We are talking about a possible eight months where you have essentially a technocrat running the country," said Marcus Noland, a specialist in Korean issues at the Peterson Institute for International Economics.

"So the current situation - the UN sanctions, a new US president and political upheaval in the South is almost a perfect recipe for the North Koreans to do something provocative," Noland said.

N. Korea military drill targets South's presidential office
Seoul (AFP) Dec 11, 2016 - North Korean leader Kim Jong-Un conducted a large scale military drill targeting South Korea's presidential Blue House, state media said Sunday.

The military exercise of the North's special operation forces -- carried out as Kim watched with binoculars at an observation post -- was aimed at "destroying specified targets of the enemy," including the South's Blue House, KCNA said.

The ruling Workers' Party newspaper Rodong Sinmun also carried a two-page report of the drill, showing several pictures of a building resembling the Blue House being invaded by the North's troops and set on fire, as well as one of Kim roaring with laughter as he watched the simulated attack.

"Through the combat drill, our forces extended the sea of fire of the Yeonpyeong Island to the sea of fire of Cheong Wa Dae," KCNA said, referring to the South's border island which was bombarded by the North in 2010.

No date was given for the military exercise.

"Well done, the enemy troops will have no space to hide themselves, far from taking any counteraction," KCNA quoted Kim as saying.

There are growing concerns of fresh provocation by Pyongyang following Friday's impeachment of South Korean President Park Geun-Hye.

Prime Minister Hwang Kyo-Ahn, who has temporarily taken on the role and authority of acting president, held an emergency cabinet meeting and ordered the military to be extra vigilant against the North.

North Korea has conducted two nuclear tests already this year and multiple missile launches in its push for a weapon capable of delivering a nuclear warhead to the US mainland.

The UN Security Council slapped its toughest sanctions yet on the North this month for its fifth nuclear test in September, capping the North's annual coal exports -- its top external revenue source.