Vietnamese dissident bloggers and democracy advocates are being kept under police watch at their homes as U.S. president Donald Trump prepares to meet for talks this week in Hanoi with North Korean national leader Kim Jong Un, sources in Vietnam say. Speaking on Tuesday to RFA's Vietnamese Service, Nguyen Lan Thang-an activist blogger and frequent contributor to RFA-said that authorities are watching him closely at his home in Hanoi, adding that he is largely unaware of what is happening now in the capital. "I do see that communist regimes like those in North Korea and Vietnam have been successful with their propaganda, though," Thang said, speaking to RFA reporters via livestream on his Facebook page. "Even those Vietnamese who have not been picked for media interviews have had positive things to say about the Trump-Kim summit in Hanoi," he said. "Most common people here have no idea how miserable the lives of North Koreans are under the Kim family's rule." Also speaking to RFA, writer and activist Ngo Duy Quyen and his wife Le Thi Cong Nhan-a well-known dissident, rights lawyer, and former member of the banned Bloc 8406 democracy movement-said that their apartment on the third floor of their building in the capital is also being watched. Cameras have meanwhile been set up outside the home in Bac Giang province of former teacher To Oanh, who once traveled to the U.S. to speak about human rights concerns in the one-party communist state, To Oanh said. "Senior security officers also came to see me and ordered me to stay home until the summit is over," he said, adding that he poses no threat to the Feb. 27-28 U.S.-North Korea talks, in which the U.S. is expected to press Pyongyang to follow through on previous pledges to end its nuclear weapons program. "Is it really likely that my name would appear on a list of suspected terrorists?" he asked. 'I might go anyway' Dissident blogger Nguyen Truong Thuy meanwhile told RFA he had been visited on Sunday by three police officers and the head of his neighborhood group-a committee set up to address community concerns and report to authorities on residents' activities. "They came to my house and asked me not to go to welcome Trump and Kim," he said. "I told them that for the time being, I had not intended to go. But then a police officer said I had just given my commitment not to go, and I told them "No,' that I rely on the law and have not made any verbal promise or commitment, and that I might change my mind and go anyway," he said. "There have been cases now where some have been locked in from the outside, to keep them from going out," added the wife of activist blogger Dung Voa, surnamed Hue. "Others are being kept under close watch, and if some manage to go out, they are closely followed," Hue said. "They don't want us to accept any invitations from foreign embassies to join them for a talk," she said. A disturbing record Ahead of this week's talks, three U.S. lawmakers called on U.S. President Donald Trump to raise human rights issues with officials in Vietnam during his visit to the one-party Communist Southeast Asian nation for a meeting with North Korean leader Kim Jong Un. In a letter dated Feb. 19, U.S. House of Representatives members Zoe Lofgren, Chris Smith, and Alan Lowenthal-co-chairs of the Congressional Caucus on Vietnam-expressed concerns that Hanoi is hosting the second U.S.-North Korea summit scheduled for Feb. 27-28, given Vietnam's poor rights record. The lawmakers highlighted what they called Vietnam's "disturbing record" on prisoners of conscience, pointing to a list released last year by London-based Amnesty International that includes nearly 100 dissidents jailed for expressing views critical of the government, and who they said endure "alarming" treatment in detention. The request from the three U.S. representatives followed two separate letters from Vietnamese intellectuals and activists, urging Trump to help thwart China's gradual takeover of the South China Sea, where Hanoi and Beijing are embroiled in maritime territorial disputes. China's claims and construction of artificial islands in the region have sparked frequent anti-China protests in Vietnam, which the one-party communist government in Hanoi fears as a potential threat to its own political control.