The Wall Street Journal reported yesterday that legal concerns contributed to delaying the decision to arm the Syrian opposition:

At the State Department, lawyers reviewing the proposals found themselves at odds with their more forward-leaning bosses—former Secretary of State Hillary Clinton and now John Kerry—who both pushed a reluctant Mr. Obama to ramp up military support to the rebels, including through the provision of arms.

Some of the lawyers involved were uncomfortable with what they saw as a policy that could be seen as similar to the Reagan administration’s backing of Nicaragua’s Contra guerrillas in the 1980s.

Some of them cited a 1986 decision from the International Court of Justice on the American role in Nicaragua that said the U.S. was in “breach of its obligation under customary international law not to intervene in the affairs of another state.”

The U.S. has so frequently ignored that obligation in just the last twenty years that it seems almost quaint that anyone at the State Department would have thought to bring it up. This sort of aggressive meddling in the affairs of other states usually has very poor legal justification and sometimes has none at all, but that is irrelevant to advocates for intervention. It’s quite difficult to fulfill an obligation not to intervene in the affairs of other states when there is a broadly shared assumption that the U.S. has every right to intervene wherever and whenever it wishes.

For many Republican Syria hawks, the comparison with Reagan’s Nicaragua policy would be an argument in favor of intervention. There is still a tendency on much of the right to lionize Reagan’s more hawkish foreign policy decisions even when they were serious mistakes, and so the policy of arming insurgents in strategically irrelevant conflicts is held up as an example to follow instead of the mostly senseless waste that it was. Republican hawks today consider the fact that Reagan supported arming insurgents in foreign civil wars during the Cold War as justification for doing the same thing now.

Another concern was that arming the Syrian opposition would provide Assad with an excuse to retaliate against Americans:

Members of the so-called Lawyers Group of top legal advisers from across the administration argued that Mr. Obama risked violating international law and giving Syrian President Bashar al-Assad the legal grounds—and motivation—to retaliate against Americans, said current and former officials.

It’s surprising how rarely this possibility has come up in the Syria debate. Opponents of the Libyan war warned against inviting retaliation from Gaddafi, and supporters of the war used Gaddafi’s past support for terrorism part of their argument for why overthrowing him would make Western countries more secure, but this has been mostly absent in arguments about Syria. It’s a valid concern, and it’s one more reason to doubt the wisdom of meddling in another country’s civil war.

A few Syria hawks have tried making the unpersuasive case that failure to intervene in Syria aggressively enough could result in retaliation against the states that didn’t intervene on the side of the rebels. Here is the latest version of the “vengeance” doctrine from the head of the Syrian Emergency Task Force:

“I think there would be a lot of people who would want revenge from the people who allowed this to happen to them,” he added, seemingly evoking a future in which a disconcerted group of rebels violently lash out against Americans if the U.S. doesn’t do more to bring down the Assad regime.

One might call this the interventionist extortion argument: we have to help these rebels, or they will attack us later. Syrian rebel attacks on countries that didn’t provide enough help isn’t a very likely scenario, and it is some of the most confused, counterproductive pro-war propaganda imaginable. Persuading skeptical Americans to support intervention in a foreign conflict is difficult enough when Americans sympathize with their cause, but it becomes impossible when Americans are being implicitly threatened with future attacks if they don’t comply with demands for assistance.