President Obama said he is "absolutely convinced" that Khalid Sheik Mohammad, the self-proclaimed mastermind of the 9/11 attacks, will be subject to "the most exacting demands of justice" when he faces trial.
Attorney General Eric Holder is expected to announce today that Mohammad and four other high-level Guantanamo Bay detainees will be tried in federal court in New York.
"This is a prosecutorial decision as well as a national security decision," Obama said today in Tokyo during a brief press conference with Japanese Prime Minister Yukio Hatoyama at Kantei, the prime minister's official residence.
"The American people insist on it. My administration will insist on it," the president said of the terror prosecution.
Asked about the delay in announcing a new U.S. strategy in Afghanistan and what information he's lacking, Obama said it was not because of "some datum of information I'm waiting on."
"It is a matter of making certain that when I send the young men and women into war and I devote billions of dollars of U.S. taxpayer money, that it's making us safer," he said.
"Those who are recognize the gravity of the situation and recognize the importance of getting this right. and the decision will be made soon," the president said. "It will be one that is fully transparent so that the American people understand exactly what we're doing and why we're doing it and what it will entail."
White House sources say the president took the advice to heart from former secretary of state and one-time chairman of the Joint Chiefs of Staff Colin Powell who told the president to take his time since the decision would impact every day of his presidency. It's advice, officials said, that was repeated by others who had made major military decisions.
The president, an administration source told ABC News, was also greatly impacted by cables sent by U.S. Ambassador to Afghanistan Gen. Karl Eikenberry (Ret.) who cautioned the president to hold off on sending more U.S. troops until the government of Afghan President Hamid Karzai more firmly commits to combating corruption and improving its governance.
Obama said he is "very pleased" with how the strategy review is proceeding.
After their meetings in Tokyo today, Obama and Hatoyama focused on the areas their nations can work together and glossed over the areas where they have differences.
The two leaders reaffirmed the alliance between their nations and pledged to work together on the issues of nuclear non-proliferation and climate changes.
The Japanese government announced this week it would provide $5 billion in economic assistance to Afghanistan over the next five years, making the Asian nation one of the largest donors.
"This underscores Japan's prominent role within a broad international coalition that is advancing the cause of stability and opportunity in Afghanistan," Obama said.
But as it announced the Afghanistan aid package, Japan also reaffirmed its pledge to end in January its refueling mission aiding U.S. ships in the Indian Ocean. Hatoyama said that decision was based on an assessment of how many times the ships had been used and what was the best use of Japan's resources.
"We have to consider the meaning of this logistics support and we've come to think there's another type of assistance that is more appropriate from Japan," Hatoyama said through a translator. The prime minister cited fighting poverty among the Afghan people as a way the Japanese can be more helpful.
In a statement issued before their press conference, the two leaders agreed to work closely on nuclear non-proliferation issues and said it "remains vital for North Korea and Iran to uphold and adhere to their respective international obligations" on this issue.
Japan announced today that it will host a nuclear security conference for Asian countries in Tokyo in January 2010.
Obama said today that Japan "unique perspective on the issue of nuclear weapons as a consequence of Hiroshima and Nagasaki."
No Announcement on Future of Contentious U.S. Military Base
The ongoing dispute about the Marine Corps Air Station Futenma on the Japanese island of Okinawa threatened to overshadow the meeting between Obama and Hatoyama.
In 2006, the two nations agreed to shut down the air base and replace it with a facility in a more remote part of the island.
Hatoyama indicated this summer, before his election, that the base should be moved completely off Okinawa, a statement that was greeted positively by residents who have pushed for a reduction in the U.S. presence there.
No final decision on the Okinawa issue is expected on this trip, but today Obama said he and Hatoyama discussed this issue and he hoped a decision would be reached quickly.
"Our goal remains the same – to provide for the defense of Japan with minimal intrusion on the lives of the people who share that space," he said.
Secretary of State Hillary Clinton and her Japanese counterpart agreed this week to form a committee to resolve the issue.
A senior administration official downplayed the dispute today, calling the issue of Futenma base "one operational subset of a huge, healthy and very complication alliance."
Earlier this week, Jeffrey Bader, National Security Council senior director for East Asian Affairs, said the issue of Futenma was not "ripe for resolution or a focus" of the president's visit and discussion will continue to work out differences.
"I don't see the Okinawa base issue being a dominant or essential issue on the visit," Bader said.
Obama had dinner with Hatoyama this evening. On Saturday he will deliver a speech focusing on the U.S.-Japan alliance and will meet the Emperor and Empress of Japan at the Imperial Palace. The Palace was the seat of the Tokugawa Shoguns who ruled Japan for more than 250 years starting in the early 17th century.
Obama Visits Troops in Alaska Before Arriving in Japan
On his way to Asia, Obama stopped to visit U.S. troops at Elmendorf Air Base in Anchorage, Alaska.
The president has not yet decided on a new strategy for Afghanistan and Pakistan and delayed the start of this trip in part so he could hold his eighth meeting with his war council.
At Elmendorf AFB, the president spoke directly about his decision to send troops into combat, without specifically mentioning the ongoing debate over Afghanistan.
"I will never hesitate to use force to protect America," Obama said to a crowd of approximately 2,000 service members and their families. "I will not risk your lives unless it is necessary to America's vital interests. And if it is necessary, the United States of America will have your back. We'll give you the strategy and clear mission you deserve….That is a promise that I make to you."
Before his address, Obama met with the family of a soldier who was killed in Afghanistan. He also met with about a dozen troops as he often does on visits to military bases, as a way to hear directly from service members about their experiences on the ground.
Obama, the first U.S. president born in Hawaii, the 50th state to join the United States, noted that this was his first time to Alaska, the 49th state to join the union.
"Up until today I had visited 49 states, so this is officially my 50th state," Obama said.
Wide-ranging Agenda, but No Tangible Results for Obama in Asia?
The president has a wide-ranging agenda for this first trip to Asia. White House officials said this week he will address trade issues, climate change, the war in Afghanistan and nuclear non-proliferation, including continued talks on Iran and North Korea.
But officials were reluctant to say what tangible results Obama will achieve, instead focusing on the ongoing discussions he will have on these subjects.
After Japan, Obama will make stops in Singapore, China and South Korea, and will meet with the leaders of those nations. He will also hold side meetings with other world leaders such as Russian President Dmitri Medvedev.
ABC News' Rachel Martin contributed to this report.