TOKYO (Kyodo) -- The top five Japanese defense firms tallied sales of $10 billion in 2023, up 35 percent from the year before, according to an international security think tank, as the country continues its defense buildup amid Chinese and North Korean threats.

Globally, the combined arms revenues of the world's 100 largest arms-producing and military services companies rose 4.2 percent to $632 billion, the Stockholm International Peace Research Institute said in an annual report, citing increased demand for weapons worldwide.

Companies in regions where wars are being waged marked the largest percentage increases, with the two Russian companies with available data and six Middle Eastern firms on the list seeing combined sales climb 40 percent and 18 percent, respectively.

Asia and Oceania saw a 5.7 percent rise, with Japanese and South Korean companies leading the growth in the region.

Among the five Japanese companies in the top 100, Mitsubishi Heavy Industries Ltd. racked up the highest revenue of $3.89 billion in 2023, up 23.9 percent, followed by Kawasaki Heavy Industries Ltd. which generated $2.06 billion, up 16.4 percent. Fujitsu Ltd., NEC Corp. and Mitsubishi Electric Corp ranked third through fifth.

"The respective military-related domestic orders of all five were at least two times, and in some cases more than four times, higher in value than in 2022 when Japan launched its biggest military buildup program since the end of World War II," SIPRI said, citing Japan's growing demand for new aircraft and missiles.

In the National Security Strategy revised in late 2022, Japan pledged to almost double its annual defense outlays in five years and advance domestic defense production and technology bases, as it faces security challenges from China, North Korea and Russia.

The aggregate turnover logged by four South Korean companies grew 39 percent to $11 billion, with Hanwha Group posting $5.71 billion in revenue, a 52.7 percent surge, supported by export contracts with Australia, Poland and Britain for artillery and armored vehicles.

The sharp growth in arms revenues among South Korean companies came as they are "trying to expand their share of the global arms market, including demand in Europe related to the war in Ukraine," Xiao Liang, a researcher with the SIPRI Military Expenditure and Arms Production Program, said in a press release issued on Dec. 2.

Taiwanese weapon system provider National Chung-Shan Institute of Science and Technology -- the only Taiwanese firm in the top 100 list -- increased revenues by 27 percent to $3.22 billion on domestic orders for missiles, drones and radars amid growing tensions with China, which sees the self-ruled island as its own territory, the report said.

Chinese companies had the second-largest aggregate arms revenues after U.S. companies at $103 billion, but they recorded their lowest growth of 0.7 percent since 2019 due to the country's slowing economy, it said.

The 41 companies in the top 100 based in the United States saw arms revenues total $317 billion, half the combined total of the 100 companies and 2.5 percent more than in 2022.