Rule X gives the committee the ability to disclose classified information unilaterally after five days, so long as the president doesn‘t object to the decision. If Trump did want to keep the document classified, he could have objected by providing a written statement outlining the national security threats that such a disclosure posed.

Even then, the committee would have been able to vote to send the memo to the full House of Representatives, which would then have its own vote on whether or not to release it.