The difficulty with this and most questions of war or even politics generally is that good definitions are hard to come by. Especially in todays age. That said, this definition of war is not nearly well defined enough. What does directly opposed mean in practice? Proxy conflicts? Taiwan? South China Sea? Declarations of war? U.S. personnel or private troops in live combat? Drone or space or cyber warfare realms? Information warfare already exists, as does other conflict - but what crosses the line into war? Certain policies measures invoked short of a war declaration? Thereafter, whose view do we take as authoritative should there be reasonable disagreement in analysis (which there will be).

@JusteM Good question. This will resolve YES if we see kinetic involvement targeting material and personel of both sides against each other. Basically both need to bomb each other. This implies that an involvment akin to what the USA is doing in Ukraine or Israel would not resolve as YES. If that happens, we will know. And there probably will be no disagreement about it.