Complex sentence: Some have argued that the most critical issue NATO faces arises from Afghanistan; and this involves developing a comprehensive strategy which brings non-NATO regional powers into a discussion about how best to proceed in short-and longer-term time frames.
Split into simpler sentences: Some have argued that the most critical issue NATO faces arises from Afghanistan. Any NATO discussion about Afghanistan involves developing a comprehensive strategy which brings non-NATO regional powers into a discussion about how best to proceed in short-and longer-term time frames.