North Korean leader Kim Jong-Un has warned of a creeping "cultural invasion," reflecting his government's growing concern over its inability to keep the outside world at bay.
In a speech at the closing ceremony of a conference for top ideological officials from the ruling Workers' Party, Mr Kim also stressed the need to intensify indoctrination efforts and prevent the emergence of "factionalist partisans".
In December Kim had his uncle and former political mentor, Jang Song-Thaek, arrested and executed, an act he later hailed as a vital blow to "factionalist scum" within the party.
The North Korean regime has successfully isolated its population from the outside world for decades, but the prophylactic power of that information barrier has diminished in recent years.
Smuggled Chinese mobile phones allow people near the border to connect with Chinese servers and make international calls, while re-wired TVs allow access to outside broadcasting.
Smuggled DVDs, MP3 players and USB flash drives bring in everything from news to South Korean TV dramas that are passed from person to person, despite repeated crackdowns.
"We must set up mosquito nets with two or three layers to prevent capitalist poison being persistently spread by enemies after seeping across the border into our territory", Kim was quoted as saying by the North's official KCNA news agency.
"We also have to take the initiative in foiling the imperialists' plots for ideological and cultural invasion," Kim said.
Constant surveillance, heavy indoctrination and the threat of prison camp terms or even execution appear to have done little to curb demand for outside news and entertainment.
Low-priced DVDs and USBs loaded with mostly South Korean TV series and soap operas are readily available at black markets, defectors from the North say.
An unconfirmed report by South Korea's conservative JoongAng Ilbo daily in November suggested that 80 people had been executed in one crackdown on the spread of foreign dramas.