https://web.archive.org/web/20190619013324/https://giaophanphucuong.org/gioi-thieu/cac-vi-chu-chan-cua-giao-phan-10311.html
Who Was This Mystery Bishop?
Fr. Miller testifies:
"We returned to Washington, D.C., to the same hotel, where a Vietnamese bishop greeted us...his valet at one time. I don't remember if it was in Vietnam or while he was in Rome. These were men he had either been an archbishop to, or had elevated to the bishopric to make them bishops. But they were all Novus Ordo. And they were stationed at Conception, Carthage, Missouri...
Was this Bishop Cua who Greeted Them?
Bp. Cua was residing at the time at the Carthage monastery in Missouri with Fr. Thiep and Fr. Dien, and the rest of the members (see photo below of Bp. Cua in Carthage). It seems like he was also part of the plan. Bp. Cua had been ordained a deacon by Abp. Thuc in 1941. However, he had been chosen as an Auxiliary Bishop under PVI when PVI was appointing Communist friendly candidates. Bp Cua traveled extensively outside of Vietnam, even while an Auxiliary Bishop in Vietnam. He developed a heart problem, and officially retired as Auxiliary Bishop in Vietnam in 1982. From then on he lived outside of Vietnam, especially in Carthage, Missouri, during this crucial time in the life of Abp. Thuc.
Bp. Cua is known to have visited the Vietnamese Buddhist monks in France. The head of these monks was named Thich Nhat Hanh, and was suspected by some of aiding the Communist government.
https://en.wikipedia.org/wiki/Th%C3%ADch_Nh%E1%BA%A5t_H%E1%BA%A1nh#Explanatory_notes

Center Bp. Cua and at right Fr. Thiep
From the above biography of Bp. Cua: 1958-1964 Bp. Cua went to France to learn about and live with the Ho Chi Minh Buddhist Association French Love (Foyer de Charite). (6 years!)
The Buddhist group founded in 1958 in France was the Association Bouddhiste de France, established by Thich Nhat Hanh during his visits to the country. This organization laid the groundwork for the later development of Plum Village, the monastery and meditation center near Bordeaux founded by Thich Nhat Hanh in 1982.
https://vn-buddhist.blogspot.com/2013/02/thich-nhat-hanh-kp-agent-in-monks-robes.html
This source linked above, and others particularly from Vietnamese diaspora communities opposed to the communist government, describe him as a "KP agent in monk's robes" who allegedly furthered communist propaganda during the Vietnam War.
"According to the CIA, he was a cadre who helped infiltrate South Vietnam and staged events like monk self-immolations to turn global opinion against the South Vietnamese government and the U.S. involvement.
To gain an overview of the Communist Party´s cadres in monk's robes, Thich Nhat Hanh & Co. and the UBCV following CIA docuмent is very revealing:Language: English, Docuмent Pages: 13, Date: 04 May 1967 Collection: Central Intelligence Agency Collection, Media Type: Docuмent, (pdf.) Full Text: Full text is available for this item. Return to the Virtual Vietnam Archive and search for Item Number: 04,109,128,007th Go to the More Information section and change to the full-text view;. View Item: situation appraisal of Buddhism as a Political Force Current During Election Period Extending through September 1967, 04 May 1967, Folder 128, Box 09, Central Intelligence Agency Collection The Vietnam Center and Archive, Texas Tech University. Accessed 21 Aug. 2012th 10. "In the background the coup had the approval of the American side by the CIA, which wanted to exploit this movement for their interests. At that time, the U.S. wanted to intervene in the war-related events directly and was not about providing indirect military assistance by supplying weapons and advisers. Consequently, a disempowerment of the South Vietnamese president met with their strategy. After a successful coup against the South Vietnamese, with the help of the CIA, KP agent Thich Tri Quang continued his strategy to direct the South Vietnamese Buddhist population in his spirit, this time by causing unrest against the new temporary "military government" and the Americans. However, his strategy was seen through. He was overthrown by the South Vietnamese and the CIA and put behind bars. He managed to get released relatively quickly through the help of accomplices within the circle of influence of the South Vietnamese government and from then on acted for the Communist side."
"CP cadres, monks like Thich Nhat Hanh, Thich Quang Do and the UBCV worldwide, including also Thich Nhu Dien in Germany and others are trembling at the work of the committee and the published books (about the investigation into the massacre of civilians of the Tet Offensive in Hue in 1968). The disguised leading cadres-agents in the U.S. and abroad control their accomplices, as the "Buddhist families" and try desperately to obstruct the work of the committee. They are proceeding with the most unscrupulous methods, such as murder threats, targeted killings by hit squads, etc. The most recent example happened in early August 2012 in the USA: the above-mentioned committee chairman barely escaped a targeted head shot from a distant (yet unknown) hideout. The U.S. safety authority is investigating this incident."
25." The UBCV was founded by the Communist Party in 1964 in South Vietnam. The strategy of the Communist Party to abuse religion and Buddhism as a protective shield goes back to Ho Chi Minh in the '40s. The strategy of the Communist Party was always to integrate communism so deeply into Buddhism that they would become untangleable. Therefore, communist cadres in monk's robes and also laymen, have been trained to distort, for example, Buddhist sutras. All kinds of "Buddhist groups" were established: from children's clubs, youth clubs, to "Buddhist family" to muster the Buddhists. The youths were trained similar to the military, in order to use them as "Buddhist" youths for military purposes. As part of this targeted collection/grouping for centralized control of the Buddhist population, the authentic Buddhist masters were separated from their students, isolated and finally eliminated by force. All monks and nuns were dispossessed, forced to give up their practice and were almost completely removed from the religious life so that eventually communist cadres in monk's robes resided almost exclusively in the pagodas. Only a few Buddhist masters and students were kept under house arrest. On the one hand, this should give an impression of religious repression in Vietnam. This meant that the cadre - agents of the CP - through their staged, apparent "fight" for "religious freedom fighters / peace activists" could attain the status of "dissident" abroad (e.g. Thich Nhat Hanh and Thich Quang Do). Secondly, the propaganda machine of the CP was working hard in order to spread the image of "religious freedom” existing in North Vietnam. The hollowed-out "Buddhist Church" (UBCV), which now followed the ideology of the Communist Party, though is not as of yet trustworthy enough to the Communist Party so that it came under a direct authority by the Communist Party through the so-called 'Southern National - Liberation Front'."