At this point, claims that the action was illegal are largely posturing. The War Powers Resolution allows unilateral action with after the fact notification, and whether it becomes unlawful depends on scope, justification, and whether it turns into a sustained conflict.
The White House is confirming U.S. military operations in Venezuela tonight. Let us be clear: these strikes are illegal. The President does not have the authority to declare war or undertake large-scale military operations without Congress. Congress must act to rein him in. Immediately.