Name and discuss one key element of national and international cooperation on airport security since 9/11, and include pros and cons of each.

In the United States, the most important change in airport security after September 11, 2011, was the creation of a new federal agency, the Transportation Security Administration (TSA), as a result of the passage of the Aviation and Transportation Security Act. Before then, only about five percent of bags were screened, as compared to 100 percent afterward. The heightened screening is generally considered the most successful element of TSA procedures. Disadvantages of TSA screening include the additional cost added to airfares and increased incidents of racial, religious, and ethnic profiling.
On the international level, the creation of the Department of Homeland Security restructured immigration-related policies and practices. The changes included new visa application procedures and reduction in numbers of immigrants from specific countries; the latter can be viewed as a pro or con of the practices.
https://www.pbs.org/newshour/world/911-to-now-ways-we-have-changed