The South Korean government has banned the launch of balloons into North Korea.

The practice has often been used as a tactic to share the gospel with people living in North Korea, Mission Network News reports.

Opposing South Korean politicians tried to stop the process with a filibuster prior to its passing; activists often use favourable winds to send balloons across the border with leaflets and money.

Some are concerned the new law, which is the first of its kind, will infringe on freedom of speech.

"On the one hand, the legislators who passed it say, ‘Well, no, this is really narrowly focused to make sure the people who will be penalized are people who put Korean South Korean citizens’ lives in danger through balloon launching,’ says Eric Foley of Voice of the Martyrs Korea.

"But on the other hand, the language itself of the law is quite broad. And in fact, as numerous analysts have pointed out, it actually criminalizes things that are very difficult to prosecute: for example, the intent to launch balloons."

Christians who use balloons to spread the Gospel beyond the South Korean border have recently experienced more pushback from authorities.

Foley says the law is an admission that there was no prior law preventing balloon launches.

Foley himself faces charges for his own past balloon launches.

"As a person who’s being prosecuted, I want people to understand I’m not worried," he says.

"I believe that there’s much more going on here than legislative power. I think God’s hand is at work, I know God’s hand is at work. And that’s why I have a deep peace about this.

"Today, the most important thing that we can do is not to protest a new balloon law. Instead, it's to continue to get the Gospel into North Korea."