The Greatest Threat to Homeland Security in the Aviation Sector

Background:
Over the years since 9/11, there has been a number of safety and security issues in homeland security sector. Most have been terrorism related dealing with a multitude of groups. Pandemics and surrounding health issues date back as 3,000 B.C.E. in "Hamin Mangha;" one of the best-preserved prehistoric sites in northeastern China. How ironic that we are now dealing with the COVID-19 virus which originated in the Wuhan, China not to include the Asian flu of 1957-1958.
As civilizations have flourished since the beginning of time, pandemics are nothing new. We have the Plague of Justinian that arrived in Constantinople, the capital of the Byzantine Empire, in 541 C.E. The plague decimated Constantinople and spread like wildfire across Europe, Asia, North Africa and Arabia killing an estimated 30 to 50 million people, perhaps half of the world’s population. We then have the Black Death of 1347 which hit Europe claiming almost 200 million lives in four years. The notion of quarantining people started with Venetian sailors being held on their ships for 40 days to stem the spread of the decease. Notwithstanding, the Plague of London, Smallpox, and Cholera outbreaks and the list goes on.
With the advancement of modes of transportation and technology, Homeland security approaches to address pandemics or other security issues are nothing new and learning to address these threats, whether man-made or natural, must be considered.
Question:
When looking at the specific assigned readings: National Strategy for Aviation Security of the United States of America (2018), National Strategy to Combat Terrorist Travel (2018), and other relevant readings from this week, do you foreseen the greatest threat to homeland security in the aviation sector to be terrorism or contagious diseases and why?
read below link
https://www(dot)tsa(dot)gov/videos/inside-look-transportation-security-operations-center