Republicans quickly justified the Jan. 3 operation as the necessary toppling of a dictator.

“I commend President Trump for ordering a successful mission to arrest illegitimate Venezuelan dictator Nicolás Maduro and bring him to the United States to face justice,” Senate Armed Services Committee Chairman Roger Wicker said in a statement.

Rep. Mike Rogers, R-Ala., House Armed Services Committee chairman, said the operation sent “an unmistakable message to our adversaries that we will not allow malign influence and threats to the American people go unchecked in our hemisphere.” Rogers said Maduro had  “aligned with hostile adversaries like Cuba, Iran, Russia, and China to threaten U.S. security.” 

Democrats, however, decried the unilateral strikes and capture as illegal. They also slammed it as yet another war without an exit plan.

Sen. Jack Reed, the ranking member of the Senate Armed Services Committee, called the administration’s declared objective to seize oil reserves “ludicrous” and that “no serious plan has been presented” for what comes next. 

“Last night, President Trump waged war on a foreign nation without authorization, without notification, and without any explanation to the American people,” Reed said in a statement. “Whatever comes next, President Trump will own the consequences.”

Rep. Adam Smith, D-Wash., ranking member of the House Armed Services Committee, said Maduro’s capture could destabilize the South American region and “appears to violate the very international laws and norms” afforded to U.S. allies—and could be a worrying trend for foreign relations. 

“Based on the administration’s National Security Strategy, I am deeply concerned that this may be an indication of more to come as the administration seeks to dominate the Western Hemisphere,” Smith said in a statement. 

The operation, dubbed Absolute Resolve, marked the largest U.S. military mission in Latin America since the invasion of Panama ordered by President George H.W. Bush nearly 36 years ago after the criminal indictment of that country’s leader. 

Legal experts said the lack of Congressional approval or notification marks the latest alarming trend from the Trump administration and continues a concerning precedent set by prior presidents.

“Wherever one thinks the line ought to be, the reality has been that presidents use very large amounts of military force unilaterally and Congress rarely pushes back in decisive ways,” said Matthew Waxman, a former deputy assistant defense secretary for detainee affairs, now a law professor at Columbia University. “There's often a lot of outrage in Congress, but not much firm and formal congressional action.”

Sen. Tim Kaine, D-Va., told reporters Saturday that the administration “lied” to Congress about its intentions in Venezuela.

“Members of the Senate and the public have definitely been lied to by the administration. But I'm not surprised at all. Because it was plain to me when the administration took the first boat strikes September 2. And then I reviewed the facts about the strikes in a classified setting…it was plain to me that the administration was plowing ahead and was going to do something like this,” Kaine said.

In addition to constitutional concerns, Kaine pushed the need for transparency with the public.

“It is shocking to think that we are now months and months into this Venezuela operation and the Republican leadership of the House and Senate have yet to allow even a single public hearing on this matter. And so much of what I know I am not allowed even to discuss with [journalists] or my constituents, because they only offer [information] to us in classified settings,” Kaine said. 

Jennifer Kavanagh, a senior fellow and director of military analysis at the Defense Priorities think tank told Defense One the operation marked an international expansion of the Trump administration’s domestic military actions against alleged narco-terrorists. Actions such as militarizing land along the U.S. southern border, deploying troops to U.S. cities for missions alongside law enforcement, were all done without Congressional insight or consent.

“I am generally concerned about the trend in which Congress seems to play a decreasing role in decisions about use of military force, because that's not how it's supposed to be in principle,” Kavanagh said. “In this case, my view is that Trump has now consolidated executive power to the point and made Congress irrelevant to the point where I'm not sure it would have mattered.”

While some analysts such as Foundation for Defense of Democracies Senior Fellow Mark Montgomery called the operation a “natural culmination of a maximum pressure campaign,” others, including one former military lawyer, said it appeared to be a flagrant violation of international law under the guise of anti-drug efforts. 

“It’s clearly an illegal use of force under the U.N. Charter that is being sold to the American people under the guise of law enforcement of narco-terrorism,” the former judge advocate general told Defense One. “We should all be concerned by the President’s increasing number of illegal uses of force in the region. We should not be using the military to engage in regime change and to occupy another country. These actions run contrary to international law and harm our credibility in criticizing our adversaries for the same behavior.”

The regime change and military force in Venezuela follows Trump’s inauguration promise to “stop all wars.” Common Defense, which calls itself the largest grassroots organization of veterans, said in a statement it opposed the operation, and lack of Congressional notification, adding that it mirrors past military involvement such as the decades-long wars in the Middle East.

“Veterans know how this goes: what begins as a so-called limited strike turns into another Forever War. That is precisely why the power to authorize war belongs to Congress, not the President,” the group said in a Saturday statement. “This moment marks a line crossed.”