The Su-24 was on air patrol over international waters when the incident occurred.
The Russian jet didn't violate Japanese airspace, The Diplomat noted, citing the Japanese Defense Ministry. In lieu of an offensive air force, which is banned by its constitution, the JASDF concentrates on air defense and detection operations.
Manufactured by Sukhoi, the Su-24 was first introduced by the Soviet Union in 1974. It is a fast, variable geometry jet that can reach Mach 1.6 at a full sprint and is capable of carrying nuclear weapons, although the jets are used to fit a variety of combat and reconnaissance roles.
While this was the first time in five weeks the JASDF has rushed to confront a Russian plane (the last time was to meet a large Ilyushin Il-38 "Dolphin" anti-ship/anti-submarine warfare plane), only five days earlier, the self-defense force scrambled when it detected a Chinese spy plane in the vicinity of Okinawa, far to the south, in the East China Sea, The Diplomat noted.
On December 14, the JASDF intercepted a Chinese People's Liberation Army Navy Air Force (PLANAF) Shaanxi Y-9JB electronic warfare and surveillance plane. The Chinese plane was also in international airspace.
However, despite Japan's constitutionally mandated neutrality, Japanese Prime Minister Shinzo Abe has recently moved to expand the country's defense expenditure massively over the next five years, Sputnik reported, including taking on the costs of converting its Izumo-class helicopter destroyers into true aircraft carriers capable of projecting air power far from the Japanese archipelago. The Defense Ministry's plan to acquire over 100 new F-35 Lightning II stealth jets from the United States is a key part of that.
The Defense Ministry requested on Tuesday an additional $244 billion for defense spending starting next year, Sputnik reported, which would come on top of the already record-setting $46 billion increase set by the 2018 budget.
In late October, Abe and Indian Prime Minister Narendra Modi signed a deal that would allow Indian ships the ability to use Japanese naval bases and give the JASDF access to Indian naval facilities in the Andaman and Nicobar Islands, Sputnik reported. Experts at the time told Sputnik the deal would give Japan little power in the Indian Ocean because of its constitutional neutrality, but if the Izumo destroyers are converted into true aircraft carriers, that could change the calculus of the situation.
Removing Article 9 from Japan's Constitution has long been a project of Abe's prime ministership. Sputnik reported in 2017 that Abe pledged to have the article, which mandates that Japan "forever renounce war as a sovereign right of the nation and the threat or use of force as means of settling international disputes" and bars it from maintaining "land, sea and air forces, as well as other war potential," removed by 2020, although he later walked back that timetable.