Wiktionary
force someone's hand
vb. (context idiomatic English) bring about a situation which necessitates an agent to act, often causing a plan to be executed prematurely.
Usage examples of "force someone's hand".
Second, you force someone's hand again when you visit the Havana Yacht Club and Walls and O'Brien come out to take you off the dock and offer you some sort of employment, which, by the way, is too ridiculous to consider.