Terror plot men still being questioned

The transcript discusses an ongoing investigation into an alleged Islamist terror plot in the UK, following the arrest of four men in different locations. The investigation is focused on High Wycombe, where previous links to jihadists in Syria have been noted. The arrests coincide with heightened security measures for Remembrance Sunday, due to diverse threats including potential lone wolf terrorism. The investigation is expected to continue for several days as authorities gather evidence.

How many men were arrested during the operation mentioned in the text?

What types of threats are mentioned as concerns for the authorities?