The elegant French-era villa housing the North Korean embassy in Hanoi has long been one of the Vietnamese capital's more mysterious buildings. With wooden shutters pulled tight day and night, phones that ring off the hook and guards that shoo the curious away, it is hardly a welcoming presence.
This weekend, however, it is different story. Lights are ablaze as Hanoi hosts North Korean Premier Kim Yong-il, a speedy follow-up trip to the mission to Pyongyang last week by Vietnam's top leader, Communist Party General Secretary Nong Duc Manh.
Fraternal relations between the two states - among the world's last remaining Communist nations - have never been particularly warm, so the sudden diplomatic tango is being closely watched across the region. Could it be North Korea's 'dear leader', Kim Jong-il, is eyeing Vietnam as a future model for any plans he may have for dragging his hermit state into the light?
It is an intriguing thought. When he made a surprise visit to Guangdong in 2005, there was considerable speculation that Beijing was determined to impress upon the leadership of the last Stalinist regime of the benefits of economic and social reform.
Vietnam offers a similar example, with some different wrinkles. Hanoi's reform process started later - and significantly, had to be accompanied by brisk diplomatic activity as the country emerged from years of post-war pariah status. As this column outlined last week, ties with its former enemy, the United States, were not normalised until 1995 - an event matched by rising foreign investment inflows and broader international engagement.
Reform and economic openness have been a complex, sometimes glacial affair, with the Vietnamese leadership keen to develop and drag their nation out of poverty, yet determined to keep their grip on power and ease any social tensions.
Yet a decade or so on, growth has been humming along, major foreign investors are drooling over the prospects of Vietnam's young population and the party is trumpeting targets to eliminate poverty by next year.
In that time it had to carefully juggle relations with giant powers such as China and the US, securing stronger ties even as its nationalistic leaders keep their ultimate influence at arm's length. Overall, it may well represent a more workable model for North Korea, which like Vietnam, has China as a 'big brother' neighbour to the north.
North Korea's recent moves to ease nuclear tensions have raised the prospect of an eventual peace deal on the Korean Peninsula - a move that could pave the way for a formal new relationship with not just South Korea, but the United States and Japan as well.
Many analysts believe that despite his belicosity and recalcitrance, Mr Kim above all else is keen for good ties with Washington, eyeing eventual riches in development and a counter to regional neighbours. US nuclear negotiator Christopher Hill is one who has noted the potential in the model, noting that Pyongyang should 'move on in the way that Vietnam has done so well'.
Respected Vietnam expert Carl Thayer, of the Australian Defence Force Academy, has noted how Vietnam offers political support outside the six-nation nuclear talks, no physical threat and plenty of experience in dealing with big powers, including Russia.
Officially, the North Korean prime minister will be seeking co-operation in farming and mining - two core sectors to his bankrupt economy. Other subjects may surface as well. The pair have a military relationship dating back to the Vietnam war, when North Korea secretly sent fighter pilots to help Hanoi's air defences. Over the last decade or so, Vietnam has exchanged rice for two Yugo-class minisubmarines, portable air defences and several Scud ballistic missiles, Mr Thayer said.
The two countries have not always been close, but right now their dance, it seems, is in full swing.