All depends on how you choose to define "threat to national security". I expect that was intentionally left vague.
Gotta tread carefully, though, to maintain some consistency. In comparing Saddam to Assad, both of them are guilty (yes, I'm making an assumption about Syria, but that's more about this particular argument than staking an actual position) of gassing their own citizens. The difference, which makes Saddam a threat but leaves Assad "innocent", is that Saddam had clearly demonstrated a willingness to attack neighboring countries as well, where Assad has kept his atrocities confined to his own borders. Thus, it's reasonable to support Dubya going into Iraq (regardless of the whole WMD fiasco) while questioning Hopey Peace Prize's plan (then not a plan, then maybe a plan, then we're not sure about the plan) for Syria.
Really, you are unikely to find any reliable, reasonable, objective analysis pre-Iraq war, that genuinely believed Saddam to be a danger to neighboring countries. Obviously i'm discounting analysis which was intentionally created for propaganda purposes. And we know there was plenty of that, purposefully misleading and manufactured to serve ulterior motives (Hell, even Colin Powell has retrospectively admitted to saying things to public he didn't even believe himself, and he calls it the biggest mistake of his career).
Yes, Saddam threatened Israel occasionally, but nobody really thought he was going to attack them. It was just empty threats. Beyond pro-war propaganda pieces, nobody actually believed Iraq was gonna attack any other country. There was absolutely no worthy proof of any such intentions.
Iraq did attack Kuwait 10+ years prior. But having attacked another country before doesn't mean you are going to attack another country soon, especially since you got your ass severely kicked before. Especially when you know, that the entire world is going to turn against you, and that you have no chance of committing a successful invasion. Despite his many other failings, Saddam did have a sense of self-preservation.
Your point is seriously flawed, and not supported by any military intelligence, beyond obvious, unsupported propaganda.
The only argument you can really make, is that the propaganda reports were based on some real intellegence, which for unknown reasons has never been made public. Even when so many of the people who supported the propaganda campaign, and even wrote some of, have admitted that there never was any real intelligence to support Saddam's supposed attempts to invade the surrounding countries.
Just like there wasn't any evidence of Saddam's ties to Al Qaida, which were a fairly important part of the pre-war propaganda campaign. Most Americans were brainwashed to genuinely believe Saddam had ties to Al Qaida, when in fact he had none.
I have to say, in comparison, the Obama administration feels refreshingly honest (Despite telling their own lies, like any administration tells). It's really quite staggering, how many intentional lies the Bush administration was willing to tell, to get the permission to invade a country which posed no threat to USA (Or to any other country, for that matter). And it's puzzling, how little most people seem to remember of those lies. It's like some kind of alternative reality thing, people have just *forgotten* everything that was said pre-war. As if it didn't really happen.
While I dislike many things, and intentional misleading (and lies) that the Obama administration does… It's still not nowhere as bad as the Bush administration. Some people try to say that because Obama white house has it's flaws, then it's not any different from the Bush white house. Which, frankly, is a position which is hard to take seriously. Look what Bush administration did pre-Iraq war. Spend the next few hours reading about it. It's really interesting to read about it in retrospect, because everything just seems batshit insane. Then compare it to what the Obama administration is doing now.
Yes, they both lie. They both show signs of incompetence. But there is MASSIVE difference between how far those lies, and the incompetence, are taken.
I prefer an administration that does only a 20% shitty job, instead of an administration that does a 80% shitty job. 20% and 80% are not the same.