Force somebody’s hand
Definition 1 of 1
Pro Tip 1/3Reluctant Action
Used when a person is forced to take an action they wouldn't normally choose. 
I didn’t want to move, but the rising rent forced my hand.
Pro Tip 2/3Urgency or Crisis
Often implies a situation of urgency or a crisis that demands immediate action. 
The company's bankruptcy forced the CEO’s hand to lay off employees.
Pro Tip 3/3Not Aggressive
Doesn’t necessarily involve aggression. External circumstances are usually responsible. 
The new regulations forced her hand to upgrade her equipment.