The easy rapport with Japan could be strained if Trump takes an aggressive approach on trade or Trump and Abe disagree on how best to approach North Korea.
The U.S. military comprises the greatest hope for people who desire to live in freedom and harmony, and they are the greatest threat to tyrants and dictators who seek to prey on the innocent, he said.
He presented the USA with a hat embroidered with the words "Donald and Shinzo: Make Alliance Even Greater" - a play on Mr Trump's 2016 election campaign theme.
White House officials said Mr Trump has spoken with Mr Abe by phone more than any world leader, aside from British Prime Minister Theresa May.
Donald Trump, right, Japanese Prime Minister Shinzo Abe, left, and Japanese golfer Hideki Matsuyama, centre in blue, play golf at the Kasumigaseki Country Club.
Abe welcomed Trump on Sunday with an effusive display of friendship that will now give way to high-stakes diplomacy.
The meeting promises to elevate these heart-wrenching tales of loss to the global stage as he hopes to pressure North Korea to end its provocative behaviour toward American allies in the region.
"For nearly 60 years, the military alliance we see on this base has endured a cornerstone of sovereignty, security and prosperity for our nations, this region and indeed, the entire world", Trump told the audience.
The president also said he'll go into his meetings with Chinese President Xi Jinping (shee jihn-peeng) on equal footing. "He is under growing domestic vulnerabilities that we all know about, hour to hour", said Jonathan Pollack, a senior fellow at the Brookings Institution in Washington.
President Donald Trump says it is "expected" that he'll meet with Russian President Vladimir Putin on the sidelines of an upcoming summit in Asia.
Trump's trip is to be dominated by trade and how to muster more worldwide pressure on North Korea to give up nuclear weapons. Abe and Trump will meet families of Japanese citizens abducted by North Korea.More news: Jobless Rate Jumps Over 1% In October
The first Trump-Putin meeting in person was held on July 7 on the sidelines of the G20 summit in Germany's Hamburg. Long-standing US alliances with Thailand and the Philippines have been repaired by engaging their authoritarian leaders and sidelining human rights concerns, though the White House suggested Trump may chide Duterte privately.
He is warning North Korea's heavily persecuted Christian minority will be the first to suffer if Trump doesn't back down.
Yokota Air Base serves as a critical center for coordination between American and Japanese commanders as they plan their missions, the president said.
In South Korea, Trump will visit Camp Humphreys, a newly-expanded military base that will ultimately house numerous 28,500 USA troops on the peninsula. The Trumps tossed white flower petals into the waters at the memorial in honour of those who died at Pearl Harbor.
The president has embarked upon an Indo-Pacific trip of numerous nations such as Japan, China, Vietnam and the Philippines.
President Donald Trump says he is looking forward to his arrival in Japan.
His trip got off to a colorful start in Hawaii. Can't wait to be with our GREAT MILITARY.
At each stop, Trump will urge his hosts to squeeze North Korea by stopping trading with the North and sending home North Korean citizens working overseas. He's set to make his case to Asian allies and rivals about the need to counter North Korea's nuclear threat.
It's a 12-day, five-country trip, and it comes at a precarious moment for Trump. Just days ago, his former campaign chairman was indicted and another adviser pleaded guilty as part of an investigation into possible collusion between his 2016 campaign and Russian officials.
Trade will factor heavily during Trump's trip as he tries to persuade Asian allies to agree to trade policies more favorable to the United States.
They're also rattled by his bellicose rhetoric about North Korean's Kim Jong Un. The North's growing missile arsenal threatens the capitals Trump will visit.