WASHINGTON — With Thursday’s House vote to limit President Donald Trump’s military actions against Iran, Congress took its latest stab at reaffirming its constitutional authority to declare war, part of a long-standing power struggle between the executive and legislative branches that has only grown murkier as the nature of global conflicts has changed.

But in the nearly 50 years since Congress passed the War Powers Act to prevent presidents from embarking on military actions without approval from the legislative branch, lawmakers have repeatedly failed to fully exert the powers they granted themselves to authorize or halt the use of military force.

And Thursday’s largely symbolic, nonbinding resolution — though it passed the House 224-194 and perhaps will even pass the Senate — is another example, since it probably won’t carry the full force of law.

Not once since the 1973 law was adopted has Congress successfully used it to block a president’s military actions, including some rather large-scale and long-term operations, such as President Ronald Reagan committing nearly 2,000 troops in Grenada in 1983 and President Bill Clinton committing thousands of troops in Bosnia-Herzegovina in 1995.

“They attempted to assert themselves,” said American University international relations professor Gordon Adams, “and then it just slipped away again.”

At the same time, only four times has Congress agreed to grant the president the authority to use military force since the War Powers Act passed: in Lebanon in 1983, in the Persian Gulf in 1991, and twice after the Sept. 11, 2001, attacks.