Rebels opposed to President Bashar al-Assad who have lamented for much of this year the difficulties of fighting the Syrian Air Force have displayed two new weapons that could alter their antiaircraft campaign. In photographs recently posted online, two fighters were shown holding modern variants of heat-seeking, shoulder-fired antiaircraft missiles.

The Brown Moses blog, which has been carefully following videos that have circulated from the Syrian conflict, put up a post a short while ago detailing what the blogger, Eliot Higgins, described initially as SA-14 and SA-24 antiaircraft missiles.

Matt Schroeder, an analyst following missile proliferation at the Federation of American Scientists, was almost certain that the SA-24 description was correct, but he questioned the first call, saying that the system identified as an SA-14 actually appears to be an SA-16. (Mr. Higgins has since updated his post to label the first missile as an SA-16.) The importance of these finds is the same either way, because rebel acquisition of any such new-generation missile, be they SA-14s, SA-16s, SA-18s or SA-24s, would be a significant upgrade. Previously, rebels have been seen only with SA-7s, an earlier, much less capable variant in the former Soviet Union’s suite of portable heat-seekers.

It has long been known that the Syrian military possessed more than SA-7s, and proliferation experts and security analysts have worried over the potential risks to commercial aviation if these missiles slipped from state hands. So this development, the apparent capture of complete SA-16 and SA-24 systems, will bear watching. If these weapons are turned toward Syrian military aircraft, then supporters of the uprising will have reason to hail them, and Syrian military pilots will have new grounds for worry on their next sorties. But if these are sold — and weapons of this sort are often said to fetch four- and five-figure dollar sums on black markets — and fired at commercial aircraft, then the consequences and regional security implications of the war in Syria will have become much worse.

This is especially true if the second missile really is an SA-24, one of the world’s most modern heat-seeking missiles and the subject of quite a scare this year in Libya, as we wrote about on At War in May.

It is too soon to know how this ends. But for now, one of the pictures freshly circulating from Syria is an apparent new marker in the missile proliferation. As Mr. Schroeder notes, “As far as I know, this is the first SA-24 Manpads ever photographed outside of state control.”