No, they're discrete mission strands. The reward for completing the Shangri La missions is
an additional health bar, which would be useful to acquire before starting the last Shangri La mission, as it's a complete sod - the second-hardest part of the whole game for me; maybe even the toughest. It's one of those 'magical' boss levels where you have to work out a syntax of actions in order to beat it.
EDITED: 9 Jan 2019 08:57 by MANTHORP