Japan's Prime Minister Fumio Kishida on Monday dismissed the idea of seeking a nuclear sharing arrangement with its ally, the US.

"It is unacceptable given our country's stance of maintaining the three nonnuclear principles," Kishida told parliament.

Japan, the world's only victim of nuclear bombing, has maintained its policy of "not producing, possessing or allowing nuclear arms on its territory."

Kishida's statement came after former Prime Minister Shinzo Abe suggested such a measure, saying Japan "should not put a taboo on discussions about the reality we face."

Abe was discussing the Russia-Ukraine war during a TV program on Sunday, the Tokyo-based Kyodo News reported.

The war entered its fifth day on Monday, with the latest reports indicating that Russian troops were heading toward the capital, Kyiv.

It was met by an outcry from the international community, with the EU, UK, Japan, and US implementing a range of economic sanctions against Moscow.

Russia has been further isolated as its airlines were banned from travelling in European airspace and a number of its banks have been kicked out of the SWIFT international banking system.

In his remarks, Kishida stressed that "it is not acceptable for Japan to make a nuclear sharing arrangement with the US as a deterrent amid Russia's invasion of Ukraine."

Japan and the US are close allies, cemented by a military pact under which close to 50,000 American soldiers are deployed in Japan.

Tokyo also relies on the US nuclear umbrella.

During World War II, the Japanese cities of Hiroshima and Nagasaki were devastated by US atomic bombs.

The US dropped nuclear bombs on Hiroshima -- the site of the world's first atomic bombing on Aug. 6, 1945 -- and Nagasaki in 1945 during World War II which resulted in the deaths of at least 140,000 people by the end of that year.

Premier Kishida himself is elected from an electoral constituency in Hiroshima and campaigned for a world free of nuclear weapons.