South Africa Rugby announced a radical contract overhaul on Saturday in a move designed to reverse the trend of talented players leaving the country.
Springbok coach Rassie Erasmus said the existing model had to be "disrupted".
"We have been agonising over how to keep players in the country since the game went professional more than 20 years ago," Erasmus said.
"And the bottom line is that the rand is too weak and the economy of South African rugby too small to compete.
"A South African player can earn more from a two-month contract in Japan than he can if he were to win the World Cup with the Springboks this year.
That's the reality we have to face up to.
"Once we have done our work, the new strategy could see as many as 75 players in Springbok succession planning and being financially rewarded for it. We had to disrupt the model."
An SA Rugby statement explained the changes "will see the current Springbok contracting model turned on its head, the 30-cap rule for overseas-based players scrapped and overseas clubs warned Regulation 9 will be rigorously enforced".
Regulation 9 deals with when and how frequently club players must be released for international duty.
Does this not make Bok players less appealing to foreign teams...knowing they will now lose their services for a good chunk of the year? https://t.co/yahc8xte6T— Dave Wessels (@DaveWessels) February 23, 2019
Erasmus said that Rugby SA had "told the overseas clubs that we will be enforcing Regulation 9 and will be requiring our players for up to 14 weeks of the year".
Regulation 9 states that: "A Union has first and last call upon the availability of a player for selection and appearances for a national representative team or national squad of that union and all attendances associated therewith, including training sessions."
"If the clubs don't like that then they have the option of not signing the player," he said.
"The only solution that would keep everyone happy would be if we had enough money to pay the players we wanted to keep as much as they wanted to receive -- but that's not the world we live in.
"We've got to deal with the practical realities and stay focused on our objective' which is to field the best available 23 players who really want to play for the Springboks and who are prepared to make sacrifices whether they are playing here or overseas.
"We only have a limited budget to do that' but we have many players who have the potential to become Springboks. This way' we can give them that message in a practical way.
"They will know that there is a future for them with the Springboks and that they can move up the succession ladder if their play merits it."
The announcement caused waves through the rugby world on Saturday with Rebels coach Dave Wessels among the high-profile voices to weigh in with his view on the impact it might have.