Defence is a divisive issue in Japan, as a result of World War II, has a pacifist constitution and an enduring public wariness about entanglement in US-led wars.
The spending plan will include a year-end overhaul of defence policy expected to include a call for the acquisition of longer-range munitions to fend off China, which in 2019 replaced North Korea in Japan's assessment as its primary national security threat.
Concerns about Chinese military activity in the seas and skies around Taiwan and Japan has intensified since Russia invaded Ukraine in February, because Japan worries it provides China with a precedent for the use of force against Taiwan that the United States may not immediately intervene in to stop.
The military balance has greatly changed around Taiwan, said retired admiral Katsutoshi Kawano, who served as Chief of the Joint Staff of the Japanese Self-Defence Forces for five years until 2019.
I hope defence budget discussions will get serious. In a manifesto ahead of the legislative elections last month, Kishida's Liberal Democratic Party pledged to double defence spending to 2 per cent of gross domestic product over five years, making Japan the third biggest military spender after allying the US and China, according to a 2021 defence budget ranking by the Stockholm International Peace Research Institute.
Kishida, who condemned China's action, said he would increase defence spending but has yet to say how much and how fast.
He said he didn't say whether Japan's military would be paid for by cuts to public spending elsewhere, or through borrowing or a combination of the two.
The missiles of China have given Kishida a chance to clarify his position, particularly given questions about the United States' stepping into a crisis, said Takashi Kawakami, professor at Japan's Takushoku University in Tokyo.
Japan needs to show it is ready to fight, Kawakami said.