Free Syrian Army fighters prepare a locally made weapon on one of the front lines of Wadi Al-Dayf camp in the southern Idlib countryside Sept. 14, 2014. Picture taken Sept. 14, 2014. (REUTERS/Khalil Ashawi)

Over the past few weeks, poll after poll has shown the just-launched American airstrikes in Syria and the weeks-long campaign in Iraq are quite popular. And that remains the case.

But actually, it would be more unusual if that wasn't the case. And in fact, the actions in Iraq and Syria have a lower initial level of support than almost every major U.S. military operation over the past three decades.

Gallup finds that 60 percent of Americans support the current combined effort in Iraq and Syria -- about twice the 31 percent who disapprove. And that's especially noteworthy given the war-weary American public has for years been practically begging the White House not to get involved in another war.

But in context, that 60 percent is far less than the early levels of support for the wars in Iraq last decade (76 percent), Afghanistan in 2001 (90 percent), and the first Gulf War in the early 1990s (79 percent). It's also less support than existed for smaller missions in Somalia in 1993, Afghanistan and Sudan in 1998 and Libya in 1986.

The only efforts which Iraq and Syria beat in initial popularity are the 2011 intervention in Libya, Kosovo in 1999, and Grenada in 1983. Given the negative coverage of the invasion in Grenada and the aforementioned war-weary American public in 2011, it's not surprising to see Iraq and Syria outrank those too. Kosovo also ranked as a not-particularly-popular intervention.

Only one of the 11 military actions above, it should be noted, got less than majority support. And even that (Libya) got a pretty clear plurality -- 47 percent to 37 percent.

But what do most of the major conflicts listed above have in common? They became less popular -- and often far less popular -- over time.

In politics, we like to refer to candidates whose best day was the day they launched their campaigns. In military campaigns, there's often a rallying effect at the outset. Sustaining that approval as the conflicts linger and potentially as American lives are endangered is much more difficult.

It's more likely that 60 percent is a high watermark in Iraq and Syria -- especially given the overwhelming skepticism of President Obama's foreign policy, particularly in the Republican Party. And even for a high watermark, it's not that high.