US President Donald Trump said no nation should underestimate American resolve, as he arrived in Japan at the start of a marathon Asian tour.
Addressing US troops at Yokota air base near Tokyo, he pledged to ensure the military had the resources needed to keep peace and defend freedom.
Mr Trump's visit comes amid heightened tensions with North Korea over its nuclear programme and missile tests.
It will be the longest tour of Asia by a US president in 25 years.
"No-one, no dictator, no regime... should underestimate American resolve," President Trump told cheering US and Japanese troops shortly after his arrival in Japan.
Before touching down, he told reporters on board Air Force One that he expected to meet Russian President Vladimir Putin during his trip.
"I think it's expected we'll meet with Putin," he said. "We want Putin's help on North Korea."
Mr Trump was meeting Japanese Prime Minister Shinzo Abe for lunch before the two leaders were due to play a round of golf.
Stops in South Korea, China, Vietnam and the Philippines are also on the itinerary in the coming week.