He has also said the same of South Korea, where USA troops have been stationed to counter the nuclear threat of North Korea, with which the South is technically still at war.
He will be the first Asian leader to meet Trump in person on Thursday on route to the APEC summit in Peru, when he'll try to safeguard the alliance between the United States and Japan.
Trump made some worrisome comments in his campaign over Washington's commitment to the long-standing Japan-U.S. security arrangement, notably his threat to pull U.S. troops out of Japan and other U.S. allies unless they pay more for their presence.
Okamoto, a lawmaker with Abe's junior coalition partner Komeito, met Trump about 16 years ago while working at an investment bank in NY.
What can Japan expect during the next four years with Donald Trump at the helm?
Already impacted by the election campaign has been the 12 nation Trans Pacific Partnership (TPP) pact. To say, I am sure Japan is going to be just fine is naïve and misguided.
As the two nations will be celebrating 60th anniversary of their diplomatic relations next year, the prime minister said, it was important for them to discuss the programmes both countries could undertake to signify this important milestone.
These initial conciliatory remarks can not hide the heightened tensions between the two imperialist powers, which fought each other for control of the Asia Pacific during World War II.
FILE - In this October 1, 2015 file photo, sailors of U.S. navy nuclear-powered aircraft carrier USS Ronald Reagan man the rails upon arrival as some U.S. flag-shaped balloons are hoisted to welcome them at the U.S. Navy's Yokosuka base in Yokosuka, south of Tokyo. But in America, it was already in trouble before the election - and now looks almost dead.
Marijuana initiatives pass in eight states on Election Day
Richard Miadich, a lawyer for the Yes on 64 campaign said: "They can't sell it, but they can grow it for their own personal use". But staunch opponents that included law enforcement groups and anti-drug crusaders urged the public to reject any changes.
Abe's government had appeared to bank on a win by Hillary Clinton, with whom Abe maintained close ties.
And Beijing is braced for Trump's blows, at least initially. A separate poll by the Yomiuri newspaper on Tuesday found 58 percent saw Trump as bad for the economy - the same proportion that views him as bad for national security. President-elect Donald Trump has vowed to reject USA participation in the TPP as unfairly impacting the American economy.
FILE - Chinese President Xi Jinping and U.S. President Barack Obama attend the G20 Summit in Hangzhou, Zhejiang province.
Some diplomats say that until Trump makes key appointments, it will be hard to assess his policies on issues ranging from overseas deployments of USA troops, China's maritime aggressiveness in Asia and North Korea's nuclear threat.
While the TPP was seen as a "symbol of US commitment to the East Asia region", it was not immediately clear how big an impact Trump's withdrawal could have on America's role in region. A lawmaker in Japan's parliament on Monday mentioned the possibility of a TPP that doesn't include the USA, citing reports that Mexico's Economy Minister Ildefonso Guajardo said such a scenario should be considered.
First, will Trump reaffirm America's rock solid commitment to its treaty allies in Asia?
Then there is the question of whether Mr Trump will urge Japan and South Korea to take up nuclear arms, as he had allegedly suggested on the hustings. The pact is now under discussion in Japan's parliament, with Abe's government hoping to ratify it in the current session that ends this month. The point of an "Omiage" is to make your host look good and, in our view, Team Abe know full well that creating United States jobs and into-America investment may well be the best way to boost Trump's credibility at home.
Abe has boosted Japan's overall defence spending since taking office in 2012 while stretching the limits of its pacifist post-war constitution to allow the military to take a bigger global role. But that doesn't mean he'll have nothing to offer Abe.