The Japanese Defence Ministry has reportedly informed the ruling Liberal Democratic Party about the decision.
Initially, the two countries agreed on the price of 98 billion yen ($894 million) to upgrade the jets with the Long Range Anti-Ship Missiles (LRASM), but later the price went up to 218 billion yen (over $1.9 billion) due to shortages of electrical components and the need to update the software, according to the media outlet.
The missiles with a reported range of 900 kilometres (559 miles) are deemed vital by Japan in light of China's military buildup, the news agency said.