hard line; tough stance
Refers to an uncompromising, firm policy or attitude, often in political, diplomatic, or negotiation contexts.
The government took a hard line and entered the negotiations.
The opposition party criticized the tough stance.
強硬 is an adjective meaning 'firm' or 'hard-line', while 強硬路線 specifically refers to a hard-line policy or course of action.
路線 means 'route' or 'line', but in compounds like 強硬路線 it takes the figurative sense of 'policy line' or 'course'.
Compound of 強硬 (firm, hard-line) and 路線 (route, line), literally 'hard-line route', used figuratively for a firm policy stance.