Large telescopes do have defense applications: https://en.wikipedia.org/wiki/Space_Surveillance_Telescope Space_Surveillance_Telescope (3.5m aperture, run by the Space Force).

https://en.wikipedia.org/wiki/3.67_m_Advanced_Electro_Optica... 3.67_m_Advanced_Electro_Optical_System_Telescope

Even if this particular telescope is purely civilian, there is a case to be made that loss of funding and expertise in large telescopes will put the West at a disadvantage in the future for such things.