Marco Rubio is on a trip to Israel and Jordan this week. Jennifer Rubin recounts his remarks at a recent press conference in Jerusalem. Her summary of his remarks on Syria:

First, he noted that the United States has a significant interest in the Syrian conflict and its outcome. He pointed to the 400,000 refugees that have streamed into Jordan, creating a strain on that country. And he made the case that it is in our interest to identify and aid the “most responsible actors” there and to secure weapons, in contrast to the free-for-all that panned out in Libya.

Of course, the “free-for-all” in Libya came about because the regime collapsed thanks to the intervention of U.S. and allied forces in the conflict there. Regime arsenals were looted by former mercenaries and others. It didn’t matter that the U.S. and its allies provided direct military support to Libyan rebel forces. The “free-for-all” happened because there was no force responsible for securing weapons caches after the regime fell. Those rebel forces were not able to secure many of the old regime’s weapons, and these weapons have since been taken into other parts of Africa to supply the arsenals of armed groups in other conflicts. Hastening regime collapse in Libya made that outcome more likely.

Though it isn’t stated explicitly here, Rubio would like to recreate that outcome by supporting the opposition in order topple the regime. That would contribute to even greater regional instability, even more insecurity inside and outside Syria, and most likely even larger outflows of refugees into neighboring countries. If the U.S. has any interest in the stability of the Jordanian government, for example, sending additional weapons into Syria is the wrong thing to do. Rubio assumes that there are “responsible actors” willing and able to secure weapons already in Syria, but there’s no reason to expect that this will be a top priority of the armed groups once they receive U.S. backing.\

No less important, supplying arms will make it harder to bring an end to the conflict. Ian Garner and Jeremy Presto explain:

If the Obama administration’s goal is to convince Alawites, Christians, Kurds and Shiites to unite against the Assad regime, it does not make sense to arm a Syrian opposition; these groups view it as the biggest threat to their future in a post-Assad Syria.

Among the many, many reasons why arming Syrian rebels is a bad policy, these may be some of most important ones: it would discourage minority communities from breaking with the regime, it would potentially facilitate violence against civilians in those communities, it would eventually encourage them to seek their own weapons and form their own militias, and it would help ensure that Syria’s conflict drags on long after Assad is gone. There are very few advocates for intervention in Syria that bother to think about what will happen in the event that their policy “works” by bringing down the current regime. They often don’t consider what will follow from regime collapse because their main goal at the moment is simply to get the U.S. involved in some fashion in another country’s war.

Marc Lynch also noted the poor track record that the U.S. has in arming insurgencies:

Meanwhile, there are plenty of examples of the overt or covert provision of arms to a rebel group prolonging and intensifying conflicts, and lots of cases of rebel groups happily taking our money and guns to “fight communists” (or whatever) and then doing whatever they like with them.

Unless the U.S. goal in Syria is to prolong and intensify the war there, there is no good reason why the U.S. should provide arms to the opposition.