On Wednesday we detailed that Japanese and South Korean fighter jets quickly answered a joint Russian-Chinese long-range bomber flight over the Western Pacific. Chinese J-16 fighter jets, two Russian Su-30 fighters and an A-50 early-warning aircraft were part of the provocative flight, which also passed close to South Korea. Russia's Defense Ministry (MoD) had confirmed its Tu-95MS strategic bombers and China’s H-9 strategic bombers conducted the eight hour flight over the Sea of Japan, the East China Sea and the Western Pacific - but that at no time was any country's airspace violated.

Washington has quickly injected itself into the ratcheting situation, coming amid a diplomatic and economic standoff between Japan and China, by sending US nuclear capable bombers on patrol over the Sea of Japan.

Japan's government confirmed its fighter planes joined the US bomber patrol, which was clearly a show of force signaling China and Russia.

"We confirmed the strong resolve of Japan and the United States not to allow any unilateral change of the status quo by force, as well as the readiness of the Self-Defense Forces and the US military," Japan's Defense Ministry said in a statement.

The fresh exercise with the US Air Force was conducted in "an increasingly severe security environment surrounding our country" - it said.

The flight included a pair of US B-52 bombers, escorted by Japanese F-35 stealth fighters and three F-15 jets. Beijing had presented the prior, longer flight as routine and in accord with international law.

"We consider it a grave concern from the standpoint of Japan's security," Japan's Chief of Staff, Joint Staff General Hiroaki Uchikura, commented of the prior Chinese-Russian aerial patrol.

Chinese Foreign Ministry spokesperson Guo Jiakun responded dismissively, saying "The Japanese side has no need to make a fuss about nothing or to take this personally."

All of this is taking place as a carrier strike group is sailing close to Japan, and after weekend PLA drills saw monitoring Japanese planes come under radar lock. The US State Department has condemned this, saying "China's actions are not conducive to regional peace and stability."

Much of these tensions hearken back to Prime Minister Sanae Takaichi's words to parliament last month wherein she left open the possibility of Japan sending its military to defend Taiwan in the event of a Chinese invasion.

Amid economic and diplomatic retaliation, including on the tourism sector, Japan was hoping for more vocal help from the Trump administration while feeling Beijing's wrath, but alas it hasn't come in a political form. However, the US sending bombers for an 'exercise' does seem fairly muscular.