If the premise is such that the far left is dangerous to this country because of an unwillingness to confront a particular enemy, both phyically and ideologically, the irony of the situation is that it is the enemy thus ignored which embodies the most conservative agenda known. With some (and I do say SOME) wacked out leftists acting as little more than useful idiots for Islamism, such a premise might be considered as having some validity, but thankfully, extremely few, if any of these people are actually in power. One encounters them far more frequently on the internet, or in academia, but none with any real authority.
Seems to me that what is often lost in conversations such as these due to the partisan nature of the original setup is that if one does consider the differences between the far left and far right here, the end product of that which is being enabled is actually a far right ideology in either case. It only depends on WHICH right wing ideology -- that of the white supremecist/survivalist type goon or the Islamist goon. There is certainly a portion of the left too whacked out to realize much of anything, especially inasmuch that it doesn't take a rocket scientist to realize Islamism is virulently right wing, but there is also a portion of the right that doesn't realize that when it fights against Islamism, it is upholding LIBERAL values.
Both the far left and far right are dangerous. What I suspect here, though, is that we really aren't talking about the far left and far right, but rather the mainstream left vrs. Mainstream right. In this case, a whole different sort of conversation should ensue, especially in regards to this notion of defending the country. In this case, the mainstream left wants to defend the country more through diplomacy than raw power (carrot vrs. stick), while the right is more predisposed towads the expression of power. If people could only see that the objective here is the same, but only the methods diffrer, perhaps they would refrain from so much finger pointing.