1. COVID-19 Pandemic Impact and Disaster Crisis Management
The coronavirus disease has been spreading to many countries around the world since 2019, and its outbreaks were unprecedentedly disruptive to the global tourism industry in a negative way. The restrictions of global mobility and border closures have been selected as potential measures to stop the spread of the pandemic 
. As a result, the international tourism business was seriously influenced due the sharp decline in the global tourist demand 
. Instead of shutting down the whole tourism industry, many countries have attempted to maintain their domestic tourism business as a driving force to overcome the difficulties caused by the long-lasting pandemic 
According to Kusumaningrum and Wachyuni 
, it was likely that there was an increasingly significant demand for travel after the pandemic waves. Ivanova et al. 
also stressed that visiting friends and relatives might be a popular motivation among tourists after long-lasting lockdowns. More interestingly, according to a research by Yuni 
, 35.7% of tourists partaking in the survey decided to take a holiday immediately after the pandemic. This indicates that domestic tourists are willing to make travel plans right after the “new normal” condition. However, tourists tended to refuse to make travel decisions to the seriously affected destinations within a year in 
, while the safe tourism destinations were found to be more attractive to visitors’ travel intention after the lockdowns were removed. Therefore, it is, to some extent, reasonable for the safe tourism destinations around the world to consider re-opening their domestic tourism in order to alleviate the impact of COVID-19 and save their local tourism-and-hospitality enterprises.
Tourism is generally seen as a vulnerable sector, which might be damaged by natural disasters or man-made crises 
. As the matter of fact, the recovery process of the tourism destinations after the shocks of crises is likely to be time consuming and challenging 
. Therefore, many researchers have attempted to propose a crisis disaster management model (CDM) to enable destinations to better respond and recover quickly after the crises. Murphy and Bayley 
initiated a disaster management model stressing the four phases, including assessment, warning, impact and recovery. The authors found that there was a critical relationship between the assessment and warning stage, which provided opportunities for a tourism destination to reduce the impact of disasters and recover efficiently. More specifically, the early warnings related the disaster and efficient preparation facilitated the two examined case studies in overcoming the crisis and amazingly rebound the destinations. During the impact stage, the authors also argued that a proper assessment of the disaster impacts was significant toward the destination revitalization. The authors also highlighted the importance of the community involvement which might foster the recovery of the local tourism destinations in a more sustainable way. The policy-related measures were found essential toward stimulating the local tourism industry and the revisitation demand of tourists in post-disasters. Although Murphy and Bayley’s disaster management model has been widely adopted in coping with the natural disaster crises, it is suggested developing a more adaptive model to better deal with the unprecedented disasters at much larger scale.
further modified a more widely prevalent model which stressed key stages as including pre-event, prodromal, emergency, intermediate, long term, and resolution. However, Scott et al. 
pointed out the gap of Faulkner’s model, which does not elaborate the recovery stage, and further developed this theoretical framework by adding long-term recovery. Ritchie 
argued that the crisis disaster model should be more detailed in order to cope with different events and the degree of the crisis impact on a tourism destination. This argument makes sense in the context of the complicated and long-lasting impact of the COVID-19 pandemic. Therefore, crisis disaster management may need to take into account the staged impact of the pandemic so that the effectiveness of the response to each stage of the pandemic could be optimized.
Although the abovementioned models can be applied for tourism destination management against different types of crises, the COVID-19 pandemic is supposed to be much more complicated and unparalleled. As the matter of fact, the COVID-19 pandemic is a global health crisis, with a long-lasting impact on the global scale which have never been witnessed before 
. Therefore, the strategic response of the tourism industry might need to take into consideration different factors in order to provide an effective measure to survive different waves of the pandemic and particularly suit the context of each tourism destination. Therefore, instead of a shutdown of a tourism destination, many tourism scholars suggest that adopting a tourism destination as a green zone might be a potential measure to foster the domestic tourism recovery in a country 
. The next section discusses the tourism scholar’s perspective and the practical experiences of a few countries taking this measure to recover their tourism business during the pandemic.
2. Green Zone Initiative and Tourism Destination Recovery
The global tourism industry has been affected by the COVID-19 pandemic; its impact on the tourism sectors has been devastating and unprecedented 
. Many countries around the world have had to prioritize pandemic prevention and alleviation of the loss of human lives over economic benefits 
. Therefore, this leads to more challenges facing the tourism industry in order to survive during the crisis. According to Wieprow and Gawlik 
, very few tourism enterprises could maintain their business throughout the waves of COVID-19, while the majority faced business suspension or even bankruptcy.
Therefore, many countries have attempted to save their tourism industry by taking advantage of their safe destinations to recover domestic tourism activities. A new tourism tendency during the COVID-19 waves called “green zoning network” or “green zone” tourism has been initiated in different parts of the world. This terminology refers to a policy response from countries to cope with the COVID-19 pandemic to gain tourism resilience by facilitating all the fundamental conditions for the tourism business to regain normalcy 
. Despite the different conceptualization of a green zone in different countries, this term is commonly known as a safe tourism destination with zero cases of COVID-19 
, and the tourism activities are required to be operated in a secure way which must align with the local regulations regarding the onsite epidemic prevention and control 
. However, the practical experiences of the domestic tourism practice during the pandemic have elicited the countries to adjust the criteria of a tourism destination as a green zone, which mainly relies on the national policy in each country. In the context of Vietnam’s tourism industry, a tourism destination as a green zone has to meet additional requirements regarding good healthcare system capacity and the vaccination rate of the local people and tourists. Wilson et al. 
believe that effective vaccination for COVID-19 could be a key criterion of a green zone since the re-opening of tourism activities should also ensure disinfection at destinations. In a global context, a networking of green zones among countries has to meet tougher requirements to foster the tourism business re-opening, although the feasibility of this initiative is limited. For example, New Zealand and Australia created a travel bubble to stimulate travel demand and tourism recovery between the two countries but have had to pause it because of the increasing risk concern and pandemic control 
. Similarly, Thailand is another typical example which initiates the “Phuket sandbox” to allow green zones to rebound their tourism business 
Under the pressure of the highly transmissible variants of COVID-19, the re-opening of the tourism business at green zones may lead to unprecedented disruption. Therefore, the concern about the effective degree of the green zone initiative remains a controversial topic that is making many countries reluctant to implement it in practice. Despite the limited success of green zone recovery during the pandemic, the experiences from a few countries, such as Thailand and Vietnam, have inspired other international tourism destinations. For example, the unexpected achievements during the pandemic in Vietnam have elicited a promising scenario that effective tourism resilience could be doable, even feasible, in the current challenging stage of the fourth wave of the COVID-19 pandemic. According to a study by Van Nguyen et al. 
, there are many critical reasons why Vietnam has accomplished dual targets, including effective epidemic prevention and tourism recovery during the second and third waves of the pandemic. First of all, the epidemic prevention regulations should be strict enough to minimize the potential risks to the green zones. Lessons from Vietnam indicate that the domestic tourism could be operated safely during the pandemic if all stakeholders are highly committed to the disinfection regulations. Moreover, Vietnam was very proactive with good preparedness for the COVID-19 impact, and the policy responses were found to be effective in crisis management 
. Last but not least, Vietnam has issued all the necessary measures to improve the healthcare system, raising community involvement as well as launching proper stimulus packages to foster recovery of the tourism industry and tourism demand in the post-pandemic period 
. In general, the green zone initiative is feasible in the context of Vietnam’s tourism industry, and the targets could be achievable with small scale of the COVID-19 impact.
However, during the fourth wave of the pandemic, the green zone initiative could be reintroduced as a potential measure, despite facing more challenges. Many scholars argued that green zone tourism could be infeasible because of different obstacles. Poor collaboration among stakeholders is claimed to be a key reason that may affect the epidemic prevention during the re-opening period. Numerous studies have highlighted the fact that many tourists prefer not to wear masks at crowded tourist attractions 
. In addition, the lack of effective communication regarding safe tourism destinations has affected tourists’ travel intention in a negative way. Typical evidence from other countries was claimed to be associated with fear of traveling among tourists because of the lack of information about green zones 
and because of fake news 
. In fact, the healthcare system capacity of the green zones is not always ensured.
It is interesting to learn from Thailand where some initial success was achieved from the green-zone initiative, namely the “Phuket sandbox”, which is known as an upgraded version of tourism bubbles in other countries such as Australia, New Zealand, Malaysia or Philippines. Evidently, Thailand issued effective pandemic prevention regulations which have saved their tourism business by fostering tourism operation at safe destinations 
. According to Knight 
Thailand’s preliminary plan regarding “learning to live with COVID-19” aimed to ease quasi-lockdown rules to foster tourism recovery in Phuket in October 2021. This originated from the previous practice of the green zoning tourism initiative, namely the “No quarantine” Phuket sandbox, which has brought hope for tourism resilience in this tourism-dependent country.
In general, the typical examples from such countries as Thailand and Vietnam may inspire other countries to facilitate their green zones to recover their own tourism business. However, more research should be conducted to investigate how tourism destinations as green zones could operate their tourism business in an effective way.