Yes, most definitely. I probably should have been more clear and tad more serious. People will care about being attacked, they aren't likely to care much if some or most of the politicians making up the government are lost. They're not well liked and quite replaceable in the long term. There is also a clear line of succession in place, and to get to a point where you might paralyze the U.S. temporarily from lack of leadership is no small task. You'd have to take out the president, vice president, the entire cabinet, the governors of every state, and probably the entire state government apparatus of each state as well to ensure the governor's aren't replaced. Hell, you don't even have a good sized chunk of the population of the country in and around the capital like you do in some other countries, so you can't even exert influence over the population to the same degree as, for example, the U.S. and its allies have in Afghanistan.Anyone who cuts the head off the snake by attacking DC is going to discover the US is a 50-headed hydra. Oh, and you're going to face 300+ million really pissed off people, many already armed, who have a bad habit of invading and trashing countries for small-scale attacks much less a direct hit on their capital. If you take out the Federal government (which hitting DC isn't going to do - sure, you'll kill a lot of them but the US has had contingency plans for losing DC for at least 60 years if not more) that still leaves the 50 states with intact governments and their own militaries (the National Guard) armed with modern weapons.
The really funny thing is that even if the UN had an army of 300k soldiers and wanted to wage war on the U.S. it's not like they could do anything with them unless they've also invented mass scale teleportation technology seeing as the U.S possesses most of the air and sea lift capacity the UN has access to. That in-turn rules out pretty much any invasion of CONUS barring a land one, and good luck massing an army in Canada, or Central/South America without being noticed.