Earlier quoted context omitted.
The problem with the International Space Station (ISS) is the ISS. It was an exercise in 80s and 90s design, and you could launch an equally capable science platform at a lower cost than refurbishing the current station. One of the main reasons why NASA is reluctant to replace the existing station is that they are afraid that the program would get cancelled, and they will be left with no station.
Also the I part of ISS kept the world space research orbiting around NASA. For example Brazil make every single research that requires a station (including vehicles, modules and medical science) use the ISS. Without the ISS Brazil could for example attempt its own station, or help China instead. NASA is very powerful, but if everyone help China or Russia instead, it would be bad for USA strategically.
I am also not sure why a reduction in international collaborators for NASA would be strategically bad for the USA. I am a strong proponent of space exploration, but NASA is not an important part of US military strategy; NASA is mostly a luxury which allows the US to demonstrate its technological supremacy.