Japan will toughen quarantine inspections on five kinds of marine products it imports from South Korea, starting June 1st.
Japan's health ministry says it will double its inspection ratio to 40 percent from the current 20 percent.
The ministry claims the move is to protect people from food poisoning that occurs frequently in the summer.
Although Tokyo denies it, the measure is widely seen as retaliation against South Korea's ban on certain Japanese seafood products.
That ban was put in place because of concerns the seafood might be contaminated with radiation from the 2011 Fukushima nuclear disaster.
In April, the World Trade Organization ruled in favor of Seoul's restrictions.
The South Korean government says it'll closely monitor the situation.