The COVID-19 pandemic became a significant test for social and economic stability worldwide. Its destructive effect forces authorities to overcome negative impacts and ensure socio-economic recovery. The research distinguishes socio-economic, environmental and public health determinants of national security before and after the pandemic. The post-pandemic recovery strategy covers various perspectives: urban, tourism, employment, healthcare, economic recovery; sustainable development; innovations and investments; environment protection; social and psychological support. We develop the National Security Index. It comprises 16 indicators of economic, environmental and social proxies of national security. The Index concerns 34 European countries in 2000-2022. Several methods were applied. Firstly, the natural and Savage normalisation (to bring indicators to a comparable form). Secondly, the principal component analysis, the Fishburn formula and ranking (to define the significance of indicators). Thirdly, the additive-multiplicative convolution (to integrate individual parameters). The National Security Index showed a delayed COVID-19 destructive impact (in 2020 the Index decreased in 2 out of 34 countries). Negative trends of the pandemic revealed actively in 2021 (the Index decreased in 14 out of 34 countries) and became dramatical in 2022 (the Index decreased in 28 out of 34 countries). Factor analysis showed that national security improvement in 2019, 2020 and 2022 mostly depended on 3-4 determinants while 6 determinants became especially crucial for the national security in 2021. Summarising the results, we can single out a range of important steps to achieve the post-pandemic recovery in national security. Economic measure might be focused on overcoming inflation, government expenditures, optimisation and maintenance of the socio-economic resilience by increase of total reserves in months of imports. Environmental measures consist in strengthening energy independence (reduction of energy production and distribution losses, fall of greenhouse gas emissions). Social measures are simulating employment. The regression analysis findings confirm no statistically significant impact of public health determinants on national security in 2019-2022.