Obama lauds Aung San Suu Kyi, gives a nod to Myanmar NEW: President Obama has a "tense" meeting with Cambodia's leader Obama meets with pro-democracy icon Aung San Suu Kyi and Myanmar's president Obama is the first sitting U.S. president to visit Myanmar, also known as Burma U.S. president encourages the country to continue a "remarkable journey" Phnom Penh, Cambodia (CNN) -- Barack Obama became the first sitting U.S. president to visit Myanmar on Monday, praising the courage of fellow Nobel Peace Prize winner Aung San Suu Kyi while also providing a symbolic nod to initial reforms in a nation once notorious for political repression. Later Monday, Obama held what an aide called a "tense"meeting with Cambodia's prime minister that emphasized the need for improving human rights in the nation hosting a summit of regional leaders. The president's trip, his first since winning re-election, overshadowed the focus his administration will place on Asia in a second term as part of a strategy to blunt Chinese influence in the region. Monday's highlight was the several hours Obama spent in Myanmar, the formerly secretive country also known as Burma. The president met with Suu Kyi at the lakeside villa where she spent years under house arrest for her pro-democracy activism. Obama called the meeting a new chapter between the two countries. "Here, through so many difficult years, is where she has displayed such unbreakable courage and determination," Obama told reporters, standing next to Suu Kyi. Myanmar was politically and economically isolated from the rest of the world for decades until it ended military rule last year. In a diplomatic show of support, Obama referred to the country by the government's preferred name -- Myanmar -- rather than the colonial name of Burma used by Suu Kyi and democracy activists. Suu Kyi warned that Myanmar's reform process would be difficult. "The most difficult time in any transition is when we think success is in sight, then we have to be very careful that we are not lured by a mirage of success, and that we are working toward its genuine success for our people and friendship between our two countries," she said. Before meeting Suu Kyi, Obama spent an hour with Myanmar President Thein Sein, whose reform drive has seen the release of hundreds of political prisoners and steps to open the country's economy. The democratic and economic reforms started by the president could lead to "incredible development opportunities," Obama said. The name Myanmar was introduced by the former military regime 23 years ago and is preferred by the country's current leaders. But until Monday, the Obama administration had largely stuck to the British colonial name of Burma. As well as meeting Thein Sein and Suu Kyi, Obama delivered a speech at the University of Yangon in which he urged the country to continue its "remarkable journey." After leaving Myanmar, Obama traveled to Cambodia for a summit of the Association of Southeast Asian Nations that began with a first round of talks and a dinner on Monday night. The president also discussed human rights issues in the host country with Prime Minister Hun Sen, highlighting the case of a Cambodian radio broadcaster sentenced to prison for something he said on air about land seizures, according to Deputy National Security Adviser Ben Rhodes. Rhodes described the meeting as "tense," in keeping with past U.S. efforts to raise human rights issues with Cambodia. Hun Sen offered no promises, but expressed a desire for closer economic ties with the United States, Rhodes said. In essence, Rhodes said, Obama was delivering a similar message in both Cambodia and Myanmar. The president's visit to Myanmar created "Obama fever" in Yangon, with crowds waving U.S. flags lining the street from the airport to greet the U.S. president. His meeting with Thein Sein took place in the nation's largest city, rather than the isolated capital. Before his trip, Obama insisted the visit was "not an endorsement of the Burmese government." During the latest eruption of tensions, the United Nations said at least 89 people were killed over two weeks of violence and 110,000 were displaced. However, some aid organizations questioned whether now is the right time for Obama to add legitimacy to Thein Sein's government. Journalist Katie Hunt and CNN's Tom Cohen, Josh Levs, Holly Yan, Gabriella Schwarz, Paula Hancocks and Dan Rivers contributed to this report.