The Philippines and Japan have long been key US allies in Asia, but Dutertehas done a dramatic U-turn since coming to office in late June.
That appeared to culminate last week in Beijing where he declared his "separation" from the United States, played down a maritime dispute with Chinaand pledged to enhance friendship and economic ties.
Back home on Saturday, however, the former mayor seemed to walk back his comments, saying he would not be severing the alliance with Washington.
And on Monday, he went further, telling Japanese media that the US will remain the country's sole military ally.
"The alliances are alive, it is there," he said in a reference to the United States, according to Kyodo News. "There should be no worry about changes of alliances. I do not need to have alliances with other nations."
Other Japanese media including the top-selling Yomiuri Shimbun quoted him as saying that all military activities with the US should be halted.
His seesawing has been closely watched in Japan, a major investor and aid donor to Manila that is wary of China's rising influence.
"It is important to have good communication and to listen directly to what MrDuterte has in mind," Japanese foreign minister Fumio Kishida, who will dine with the president later Tuesday, told reporters when asked about the firebrand leader's elusive comments on ties with Washington.
Prime Minister Shinzo Abe has worked to beef up relations with Manila by providing patrol boats and has supported it in the territorial row with China, asJapan seeks support in its own maritime dispute with Beijing.
Duterte's predecessor took Beijing to an international tribunal over its extensive claims in the South China Sea -- where it has built artificial islands capable of hosting military facilities -- and the Philippines won a resounding victory in July.
