**7. Conclusions**

Climate change is a major challenge for the global economy. Rapid industrialization has caused the exploitation and disposal of natural resources to grow at an unprecedented pace compared to the early industrialization period. The flagrant waste of resources is a major potential risk for sustainable development. However, focusing only on sustainable development would not be an appropriate approach either, since peace and security for countries is also essential. In this respect, it becomes inevitable that countries to allocate some of their resources to the defense sector. Furthermore, tensions between and within countries drive them to arms races, resulting in the allocation of scarce resources to inefficient areas. This situation is known as the famous phenomenon of "butter versus guns" in the field of defense economics. The arms races and increase in military outlays mean no only the transfer of scarce resources to the arms industry, but also increases in energy consumption and the use of natural resources for the production and use of defense products. While the direct environmental effects of militarization such as bombing and destruction manifest themselves in the short term, effects such as the reduction in forests, pollution of soil and water, decreases in production, and waves of migration manifest themselves in the long term. Thus, the association between militarization and environmental degradation should be assessed in the long term.

In light of this information, this particular study deals the asymmetric effects of the defense burden on environmental degradation for fifteen countries within NATO, which is a major power in the global context in terms human resources, logistics, and technology. In line with the majority of empirical studies in the literature, our findings support the treadmill of destruction theory. Accordingly, a negative change in the defense burden has a retarding effect on carbon dioxide emissions in the long term. Furthermore, a unidirectional causal relationship exists between negative changes in the defense burden and carbon dioxide emissions.

The treadmill of destruction theory is tested by novel methods and confirmed asymmetrically; this creates the opportunity to better comprehension the link between militarization, environment, and sustainable development. Although it is widely accepted that countries with more labor-intensive and advanced technologies demand more natural resources, the findings for the countries investigated within the scope of this study show that as military expenditure decreases, pressure on the environment also decreases. Allocating significant budgetary resources to defense expenditure in extraordinary times as wars, coups, or natural catastrophe increases air pollution, as well as environmental waste. These findings draw attention to the high level of defense expenditure in the long-term and reveal that resources become scarcer as a result of shifting existing productive resources to inefficient fields such as defense. This resource transfer process both reduces efficiency and creates problems in terms of sustainability.

In connection with these findings, studies carried on the nexus of environment and militarization in the last ten years has been partially successful. It could be argued that initiatives aimed at reducing carbon emissions and other greenhouse emissions have been effective in recent decades. Furthermore, most of NATO countries are parties to vital agreements on environmental sustainability and the reduction in the adverse impacts of climate change and greenhouse gas emissions. Thus, they are also regarded as pioneers in these terrains. The fact that some of the countries included in the sample are important arms producers and exporters at the global scale might affect not only production technology, but also the military outlays that are made over old conventional arms products. Nevertheless, the existence of standards regarding the environment and energy consumption in the EU member states of NATO might potentially affect this situation.

The subject discussed in our study helps shed light on current practices and to develop policy recommendations for defense expenditure within the framework of a sustainable development model in the future. Ensuring the usage of environmentally-friendly policies on defense technologies that avoid the consumption of fossil fuels may have a mitigating effect on environmental pollution. Through these policies, foreign dependency can also be decreased, paving the way for countries to be more active and effective politically. Awareness that increased defense expenditure in extraordinary times can increase air pollution and environmental waste can also aid in effective planning before these situations occur. Furthermore, the implementation of green growth policies can reduce the possible negative impacts of economic growth in terms of environmental pollution. NATO's future agenda includes ensuring the security and territorial integrity of member states, as well as taking action against climate change. It is inevitable that, using obsolete and less-sensitive technologies to environment, make defense activities gradually less effective. Therefore, using non-innovative and environmentally-friendly technologies also put pressure on scarce natural resources that are at risk of depletion. Thus, investments in renewable energy resources should also be given priority in how NATO members allocate resources for common defense. Actions taken within the "Green Defense Framework" developed at the Wales Summit in 2014 can also contribute to the creation of new employment opportunities and alleviate the concerns of countries regarding their economic growth while ensuring sustainability. In addition, while these actions are carried out, NATO should focus attention on minimizing conflicts of interest among members, enacting joint decision-making mechanisms, and developing relations in a peaceful framework.

**Author Contributions:** Conceptualization, S.E.G.Ö.; methodology and literature O.Ç.; software, Ö.F.B.; formal analysis, Ö.F.B.; investigation, O.Ç. and S.E.G.Ö.; resources, O.Ç.; data curation, Ö.F.B.; writing—original draft preparation, O.Ç. and S.E.G.Ö.; writing—review and editing, O.Ç. and S.E.G.Ö. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** All data included in this study are available upon request from the corresponding author.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **Appendix A**

**Table A1.** List of countries.


Note: \* countries are shown in alphabetical order.
