Sen. James Webb met with top officials in the hard-line military government of Myanmar on Saturday and arranged for the release of an American prisoner there, part of a mission that may open the door to further U.S. engagement, according to senior administration officials. Accompanied by U.S. Embassy officials, Webb, D-Va., traveled to the remote Myanmar administrative capital of Naypyidaw to hold rare talks with the country's leader, Gen. Than Shwe. He also paid an hour-long visit to pro-democracy leader Aung San Suu Kyi, who is under house arrest. He was told that Myanmar would allow John Yettaw, 54, sentenced last week to seven years for intruding on the Nobel laureate's heavily guarded home, to leave the country with him on Sunday. The agreement to free Yettaw, of Falcon, Mo., follows North Korea's release of two American journalists to former President Bill Clinton during a visit to Pyongyang earlier this month. Michael A. Hammer, a spokesman for the National Security Council, Saturday described both trips as 'private, humanitarian missions unlinked to our policies.' But a senior official said the administration sees the two visits in starkly different terms. Although Clinton was briefed by the administration before his trip, and he is expected to provide valuable firsthand information about it in formal debriefing this week, he 'has no job in the government,' the official said. Moreover, the primary purpose of Clinton's trip was to win the release of the women who had been detained. Their families had initiated the request for Clinton to travel to North Korea. The release of Yettaw, by contrast, was 'serendipitous,' the senior official said, adding that Webb went to Myanmar 'to have substantive conversations' as the head of the Senate's Foreign Relations subcommittee for East Asia and Pacific affairs. Webb 'wasn't given instructions' in administration briefings before his departure, the official said, but is 'familiar with our thinking.' 'We felt that if he could be a way of getting a message' to Myanmar's leadership about the administration's views, the trip could be useful, said the official, who spoke on the condition of anonymity, about evolving policy. Unlike with North Korea and Iran, the United States has maintained diplomatic relations with Myanmar, also known as Burma. But 'our problem is that we can't get high-level meetings' with the reclusive junta, the official said. A military veteran who suffers from diabetes and post-traumatic stress disorder, Yettaw swam across the lake behind Suu Kyi's dilapidated villa in May to warn her that he had had a vision in which she was killed by terrorists. She said she allowed him to stay overnight to overcome his exhaustion. Last week, she was sentenced to an additional 18 months of house arrest for violating the terms of her detention. Yettaw was found guilty of security and immigration violations. In an interview with the Associated Press, Yettaw's wife, Betty, said she had not received official notice of his release. 'If it's true,' she said, 'of course I'm extremely happy and we're ecstatic.' In a statement released by his Washington office, Webb said he was 'grateful to the Myanmar for honoring these requests' to see Suu Kyi and release Yettaw. 'It is my hope that we can take advantage of these gestures as a way to begin laying a foundation of goodwill and confidence-building in the future.' The administration has been exploring the prospect of better relations with Myanmar, offering to consider allowing U.S. investments -- now prohibited under economic sanctions -- in exchange for Suu Kyi's release, and allowing opposition groups, including her National League for Democracy, to participate in elections scheduled for next year. U.S. diplomats held one meeting with the Myanmar foreign minister in March and another in June. Webb planned to depart Myanmar on Sunday morning to continue his five-nation tour of the region, and is expected to brief the administration on his return. 'We'll get a sense from him about how they're prepared to proceed,' the senior official said of Webb's talks with Than Shwe. 'They have a really opportunity here ... to make (the elections) relatively credible, and we can use it as way of testing' the government's intentions. The additional sentence given to Suu Kyi put on hold the completion of an administration policy review on Myanmar. But although the sentence was 'horrible' and unjustified, a second administration official said, it was the 'least bad' of a range of possible outcomes, including far lengthier imprisonment. Officials said the administration also interpreted the turning back of a North Korean ship that wanted to dock in Myanmar last June as a positive sign. The ship, thought to be carrying suspicious cargo such as nuclear weapons components, was being tracked by a U.S. naval vessel. 'One might infer that (Myanmar) gave a signal -- don't come here because we're going to have to inspect you,' the official said. As the administration awaits information on the elections, officials say they are looking at policy options that would allow greater engagement with the Myanmar people without direct interaction with the government. Some longtime Myanmar observers saw the decisions to allow a meeting with Suu Kyi and to free Yettaw as a signal that the junta may be looking for improved relations with the West. Although the government has shown little sign of easing its repression of political opponents and ethnic minorities, these experts said that Saturday's developments represent an opening that should be exploited. They noted that Myanmar authorities had declined a request by the U.N. secretary general to meet with Suu Kyi in July. 'Senator Webb did something that Ban Ki-moon couldn't do,' said David Steinberg, a Myanmar specialist and professor at Georgetown University's School of Foreign Service. The start of a dialogue with Myanmar,which has been stalled for years, 'is important no matter how it comes out,' Steinberg said. He said the administration and Congress should now pursue a quiet diplomacy that seeks to prod the military government into real reforms, perhaps with help from the Chinese. But human rights groups saw the release of Yettaw as a cynical ploy intended to divert attention from the government's decision to extend Suu Kyi's house arrest. 'The regime played its hand perfectly,' said Jeremy Woodrum, director of the U.S. Campaign for Burma. 'They get a whole host of publicity from Webb's visit ... and they have a legal pretext for keeping Suu Kyi under arrest.' A day before Webb announced that Yettaw would be freed, the advocacy group Human Rights Watch issued a statement calling on the U.N. Security Council to impose an arms embargo on Myanmar and to create a commission to investigate allegations of war crimes. The group contends that army attacks against ethnic Shan villagers have displaced more than 10,000 people since late July. Lynch reported from New York. Staff writer Joby Warrick in Washington and correspondent Tim Johnston in Bangkok contributed to this report. 