Addressing an audience of Japanese executives — among the biggest investors in the Philippines — Mr Duterte repeated his threat to break off defence agreements with the US and expel foreign troops from the archipelago.
But he said his visit to China last week, where he announced the Philippines’ separation from the US, signalled an independent foreign policy rather than a new alliance with Beijing.
Mr Duterte’s remarks add to the confusion about his intentions towards the US and will do little to reassure Tokyo, which is alarmed at the sight of Manila, its vital strategic partner, feuding with its indispensable ally.
I went to China for a visit and I would like to assure you that all there was, was economics, he told the Japan External Trade Organisation.
我去中国作了一次访问，我想向你保证，一切都只是经济，他告诉日本贸易振兴机构(Japan External Trade Organization)，我们没有谈论武器，我们没有谈论军队驻扎。
We did not talk about arms, we did not talk about stationing of troops, we avoided talking about alliances, military or otherwise.
China and the Philippines signed 13 agreements last week amounting to a notional $13.5bn in trade and investment.
In a dramatic month of diplomacy, Mr Duterte has reshaped Manila’s stance towards Beijing, all but setting aside an international court’s ruling in favour of the Philippines over disputed waters in the South China Sea.
He repeated his harsh words towards the US, saying the Philippines was not a dog on a leash and pledging to get foreign troops out of the country within two years.
However, Mr Duterte has yet to take any concrete action after similar remarks in the past.
In contrast to his attitude to the Philippines’ former colonial master, Mr Duterte has had warm words for Japan, despite the wartime history between the countries.
He has repeatedly thanked Japan for its record of development aid and called the country a longstanding friend.
He urged Japanese companies to invest more in the Philippines.
Speaking to a group of Japanese parliamentarians, Mr Duterte seemed to go further and say Manila and Tokyo had common security interests in regard to Beijing.
When China grows bigger, it could clash with the United States, he was quoted by local media as saying.
We are in the same position with regard to China so we should join hands.
At an evening summit meeting, Mr Duterte and Japanese prime minister Shinzo Abe discussed the significance of their US alliances to Asian security, the South China Sea and Mr Duterte’s violent anti-narcotics campaign in the Philippines.
The leaders also acknowledged the court ruling on the South China Sea, a priority for Japan.
The Philippines will uphold the value of democracy, adherence to the rule of law and the peaceful settlement of disputes including in the South China Sea, said Mr Duterte, following the summit.
However, Yuko Kasuya, an expert on Philippine politics at Keio University in Tokyo, said Japan would struggle to keep Mr Duterte out of Beijing’s orbit or to act as a bridge between Manila and Washington.
然而，东京庆应义塾大学(Keio University)的菲律宾政治专家粕谷祐子(Yuko Kasuya)表示，日本将难以使杜特尔特不被拉入北京的轨道，也难以充当马尼拉和华盛顿之间的桥梁。
The overall presence and the future prospect of Chinese business and markets for the entire country is far greater than that of Japan.
Militarily, Japan’s support is negligible, said Ms Kasuya.
Probably what Japan can do is to expect the unexpected.