sudden change; abrupt shift; sharp turn
Used for a rapid, often dramatic change in direction, policy, attitude, or situation. Common in news and formal contexts.
The government's policy took a sudden turn.
His attitude showed an abrupt shift.
方向転換 is a more general 'change of direction', not necessarily sudden. 急転換 adds the nuance of abruptness.
Compound of 急 (sudden) and 転換 (change, conversion).