The U.S. legal posture towards Afghanistan, therefore, holds ongoing significance. Specifically, we need to ask the question: Does the United States still consider itself to be waging a forever war against terrorist groups in Afghanistan?
The answer so far appears to be yes, even though U.S. President Biden proclaimed that, with the withdrawal of U.S. armed forces from the territory, “the United States ended 20 years of war in Afghanistan — the longest war in American history.” But while fighting against the Taliban may be over (at least for now), Biden has also signaled that the United States will rely on  “over-the-horizon” capabilities to continue the war against terrorist groups in Afghanistan. Indeed, it seems the Biden administration decidedly has not declared the end of the forever war legal paradigm. To the contrary, the U.S. government continues to take the position that it is engaged in a broad, ongoing, transnational armed conflict against al-Qaeda and terrorist groups, including in Afghanistan, and that the dominant international legal framework governing extraterritorial operations against these groups therefore is the law of war, also known as international humanitarian law (IHL).
Why does it matter whether or not we are formally still at war?

The United States and its NATO allies are facing forceful calls to impose a “no-fly zone” over Ukrainian skies, with the idea of countering Russian aggression in the region, easing humanitarian suffering, and protecting Ukrainian civilians trying to flee the fighting. Ukraine has requested a no-fly zone repeatedly. In the United States, polling shows this is a popular idea: three-quarters of Americans support a NATO-imposed no-fly zone. But a no-fly zone does not equate to a no-combat zone. Quite the opposite. Enforcing a no-fly zone requires the use of military force, and in Ukraine, that would likely mean confronting the Russian military head-on.