Throughout the three-plus years of the Syrian civil war, one oft-sung refrain among some American officials has been that arming Syrian moderates (whoever they may be) is a dicey proposition because the weapons "could fall into the wrong hands."

Despite these objections, the United States eventually sent military aid to the Free Syrian Army last year. The policy change was precipitated by Syrian dictator Bashar Assad's violation of the Obama administration's "red line" after the regime used chemical weapons against civilians.

Last month, with the rise of ISIS in mind, Congress approved the president's plan to to train and arm the Syrian rebels. There was some familiar dissent at the time. "How will we ensure that the United States weapons we are providing to Syrian rebels will not get into the wrong hands, as they did with the rebels we supported in Libya?" Representative Barbara Lee asked.

On the same day as that vote, Islamic State fighters first encircled Kobani, a Syrian town near the Turkish border, attacking the largely Kurdish town and inspiring vigorous American airstrikes. On Monday, hoping to decisively turn the tide in the battle, the United States airdropped weapons to the Syrian Kurds of Kobani. By way of explanation, especially to a skeptical Turkish audience, U.S. Secretary of State John Kerry offered that not aiding the Kurds in their fight against ISIS is both "irresponsible" and "morally very difficult."