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.
He later told the Japanese prime minister he thought the two countries had never been closer.
It will be the longest tour of Asia by a US president in 25 years.
It comes amid heightened tensions with North Korea over its nuclear programme and missile tests.
"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."
Speaking after talks with Prime Minister Shinzo Abe, Mr Trump said: "The relationship is really extraordinary.
"We like each other and our countries like each other, and I don't think we've ever been closer to Japan than we are right now."
Earlier the two leaders played golf, when they were joined by Hideki Matsuyama, one of the world's top players - as the president mentioned in a tweet.
Playing golf with Prime Minister Abe and Hideki Matsuyama, two wonderful people! pic.twitter.com/vYLULe0o2K— Donald J. Trump (@realDonaldTrump) November 5, 2017
The US First Lady, Melania Trump, spent time with Akie Abe, the Japanese prime minister's wife, who showed her Japanese cultured pearls at shop in Tokyo's Ginza district.
Stops in South Korea, China, Vietnam and the Philippines are also on the itinerary in the coming week.
En route to Japan, the president stopped in Hawaii where he visited the USS Arizona Memorial at Pearl Harbor - the scene of the 1941 Japanese attack that drew the US into World War Two.
He also took part in a briefing at the US Pacific Command.
Mr Trump has previously exchanged some fiery rhetoric with North Korea over its ballistic missile tests but aides said earlier this week that he would not go to the heavily fortified demilitarised zone (DMZ) on the border between the South and North.
He is, however, to visit Camp Humphreys, a US military complex south of the capital, Seoul.
In Vietnam, Mr Trump will attend the Asia-Pacific Economic Co-operation summit in Da Nang and make a state visit to Hanoi.
His final engagement is scheduled to be a summit of South-East Asian nations in the Philippine capital, Manila, on 13 November but the trip has now been extended by an extra day so he can attend the East Asia Summit.
The last time a US president made such a marathon trip to Asia was when George HW Bush visited the region in late 1991 and early 1992.
President Trump's itinerary
- Sunday, 5 November: Arrives in Japan. Golf with Prime Minister Shinzo Abe and professional player Hideki Matsuyama at Kasumigaseki Country Club. Bilateral meetings with Mr Abe
- Tuesday, 7 November: In South Korea for talks with President Moon Jae-in. Mr Trump will also address the National Assembly
- Wednesday, 8 November: Arrives in China for a series of events including meetings with President Xi Jinping
- Friday, 10 November: Travels to Da Nang, Vietnam, and will participate in the Asia-Pacific Economic Co-operation (Apec) summit
- Saturday, 11 November: Travels to Hanoi, Vietnam, for talks with President Tran Dai Quang and other Vietnamese leaders
- Sunday, 12 November: Arrives in Manila, Philippines, to take part in a gala dinner for the 50th anniversary of the Association of Southeast Asian Nations (Asean)
- Monday, 13 November: Will attend the Asean summit in Manila and hold talks with President Rodrigo Duterte
- Tuesday, 14 November: He will now stay for the East Asia Summit, a wider regional gathering that includes the US, India and Russia