Nicolas Maduro's detention or harming of Venezuelan interim president Juan Guaido would justify U.S. military action against Maduro's regime.

This bears new notice in light of Tuesday's announcement by Venezuela's fake-prosecutor general Tarek Saab, of an investigation into Guaido over Venezuela's ongoing power shortage. That shortage was precipitated by years of gross underinvestment and mismanagement by Maduro and his predecessor Hugo Chavez. But Venezuela's humanitarian crisis and growing external pressure mean that Maduro needs a scapegoat. Guaido appears to be his choice.

By virtue of Maduro's manifest theft of the 2018 presidential election and Guaido's own position as speaker of the democratically elected National Assembly, Guiado is Venezuela's constitutionally vested leader. Guaido's legal authority stands in stark contrast to Saab, who holds his office illegitimately. After all, Saab was unconstitutionally appointed by the Constituent Assembly, a rump legislature that Maduro created to displace the democratically elected but opposition-controlled National Assembly. Guaido is also an American ally. And so, at least over a finite period, President Trump has the constitutional authority to use force to compel Guaido's release.

That speaks to the second factor here: Guaido's detention would also represent Maduro's crossing of an explicitly offered American red line. Secretary of State Mike Pompeo and national security adviser John Bolton have both warned that any action by Maduro or his proxies against Guaido would result in serious consequences. This threat requires a follow-through for the sake of America's credibility.

Ultimately, there's the issue of proportionality here. Until now, the Trump administration has avoided direct military threats against Maduro's regime, instead applying diplomatic and economic leverage. That has been the right approach. But if Maduro wants to alter the nature of this struggle, then Trump needs to make him understand that things can get a lot worse for him, and quick.