The answer seems to be when Americans are not dying.
Throughout the 1990's, the United States (through Bill Clinton) and Britain lead a bombing campaign in the country of Iraq that killed an inestimable number of people and caused an untold amount of damage to property and wealth in an already impoverished nation. One of the reasons the estimates of damage are impossible to know is that is the chaotic and insane nature of war. Another reason is that this war was not called "A War". By and large, it wasn't called anything. It was hardly referenced in our media, certainly not to the degree the Afghanistan and Iraq wars were later covered by 24 hour news shows, even if that coverage is now dwindling despite the never ending violence that seems to continue.
This campaign was so under-covered that many of our own ruling elite seemed to be unaware of it's existence as evidenced by Rudy Giuliani's reaction to Ron Paul evoking this campaign during a debate in 2007. Giuliani says, "I don't think I've ever heard that." And he wasn't alone it seems, as the crowd cheered on his ignorance and repudiation of Paul's statement of simple fact.
Now *everyone* knows about Iraq War II, because that was a War (with a capital W). We know this was war because that's what most every media source referred to it as. But why? What was the difference between that War, and the non-war during the 90's? One simple explanation would be that there was no declaration of war during the 1990's. But then, this CAN'T be the reason for not calling the war in the 90's a War (with a capital W), because there was no declaration of war for the second Iraq war either.
Yesterday the United States sent predator drones from Afghanistan, a country we ARE at war with, to Pakistan, which we are NOT at war with, and killed dozens of people. This attack is the fourth in the last week and has brought the death total for this week alone to nearly 100 people. This attack also marks the 25th time the United States has bombed Pakistan since Barack Obama has taken office, and the 61st attack since the beginning of 2008.
BUT, we are not at War (with a capital W) with Pakistan. There's no American's dying, the use of predator drones have ensured that as the use of Cruise missiles did in the 90's over Iraq. There's no "boots on the ground" so to speak, despite the claims on the Air Force's propaganda videos that these planes are being used to support troops and "save lives." They are in fact being used to TAKE lives. Lives of children and lives of innocents, but not lives of Americans. So there is no War.
Blowback is a bitch, as the United States learned in 1979 when 53 Americans were held hostage for over a year, and then RE-LEARNED on September 11th. The seeds the Federal Government have planted through their non-Wars take time to grow, but grow they do. It's impossible to say what will be harvested from these consistent and deadly attacks in Northern Pakistan, or if the consequences will be so clearly consequential that they will self-evidently a direct result of these attacks. But actions have consequences nonetheless. And as long as the United States Federal Government continues to act with hubris, ignoring all calls to end it's non-war with Pakistan, it runs the risk of inciting more violence against Americans, which could possibly lead to a "real" War.
The kind with a capital W, and sadly the kind with lots of American deaths.