One of the most important policy and legal questions moving forward is whether the Trump administration needs to seek congressional approval for military strikes in response to Syria’s use of chemical weapons. That question applies not only in retrospect to Thursday’s strike, but perhaps even more so to the prospect of future military operations.

As a matter of constitutional law, a conventional framework for determining whether the President can act without prior congressional authority turns on the scope of the military operations and the anticipated risk of escalation.

With that framework in mind, what should we make of the fact that President Obama ultimately sought congressional approval prior to striking Syria in response to Assad’s use of chemical weapons, but Trump didn’t? However, one comes out on that query, there are two facts to consider.

Scope of military operations

The scale of Obama’s military operations in 2013 was reportedly far more expansive than Trump’s more limited April 6 strike.

Obama’s military operations were to last one or two days and were “aimed at military units that have carried out chemical attacks, the headquarters overseeing the effort and the rockets and artillery that have launched the attacks,” according to the New York Times. “An American official said that the initial target lists included fewer than 50 sites, including air bases where Syria’s Russian-made attack helicopters are deployed. The list includes command and control centers as well as a variety of conventional military targets.” Colin Kahl described the reported 2013 plans as similar to “saturation strikes” that President Trump rejected. Trump, as we know, instead opted for a short-duration, one-off strike on parts of the airport at Shayrat, deliberately leaving the runway intact.

In 2013, the United States also planned to act in concert with French military forces. France reportedly loaded its fighter jets with cruise missiles which were set to launch their munitions while over the Mediterranean.

The take home point: Obama had even more reason to obtain congressional approval before launching an operation of such a scale. If his legal team did not deem it legally necessary to do so in 2013, then there would presumably be even less reason for Trump’s legal team to do so in 2017. Similarly, if Obama thought it was legally or otherwise prudent to go to Congress for such a massive operation, it would not necessarily imply that Trump should consider it prudent to do so for a much more limited operation.

Risk of escalation

On the other hand, there was something missing in Syria in 2013 that was present on April 6: the Russian bear. President Trump’s strike occurred while Russia has been backing up the Syrian regime and militarily coordinating operations with Assad’s forces. When dealing with a nuclear power like Russia, how should one consider the risk of escalation for determining whether the President should seek congressional approval? Surely even a low-to-medium risk of hostilities with a nuclear Russia raises greater concerns than even a super high risk of hostilities with countries like Grenada or Panama.

What is more, there is “mounting evidence” that Russia was complicit in the Syria chemical attack itself, according to Senator Richard Blumenthal. A U.S. official told CNN that intelligence showed a Russian drone flying over the location before the chemical attack occurred. And on this past weekend’s Fox News Sunday, the president’s National Security Advisor, General H.R. McMaster remarked, “how could it be” that Russia didn’t know Syria was “preparing and executing” the chemical weapons attack given Russian advisers at the Shayrat airbase.

Indeed, this raises the question whether the Trump administration was aware of potential Russian involvement in the chemical weapon attack before launching a strike in retaliation. It is probably too provocative to ask: how could it be that the Trump team didn’t? But a more modest question of whether the Trump team did know of potential Russian involvement is a valid one.

The take home points: Russia’s connection to the very cause of the U.S. retaliatory strike (plus the presence of Russians at the Shayrat airbase, before being warned away by the United States) is a significant variable that the Obama team did not have to consider. If risk of escalation is a factor in the analysis of whether the president must obtain congressional authorization, these were reasons that the Obama team did not have, but the Trump team did, to go to Congress first.

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[Update:] What’s next? Russia has taken multiple provocative steps in response to the April 6 strike, which goes to show how quickly things could escalate in the future. Regardless of what information the Trump team had prior to the April 6 operation, the information we now have provides even stronger reasons for President Trump to get congressional approval before engaging in future military actions against Syria. At that point we will likely be a big step up the ladder of escalation–in the expanded scope of US military operations (no longer just a one-off), in the knowledge of Russian involvement in chemical weapons use, and in the prospect of militarized Russian-Syrian responses.