The underlying reason for a current account deficit can differ from case to case; it can be trade-induced via export weaknesses, indicating a lack of competitiveness; it could also reflect strong import demand due to unsustainably high growth. This leads us directly to internal imbalances, which comprise accumulated private and public debt, asset price bubbles, unemployment or excessive inflation (or deflation).
One could also add sectoral or distributional imbalances contributing to uneven growth. Internal and external imbalances are often interlinked, but their interrelation is not always clear-cut.