“Reacting” may be too generous description. As much as I admire U.S. President Barack Obama for his strong points (there are some), making heads or tails out of his foreign policy theology would require special tools.
Here is a country — Ukraine — emerging from a successful, some would say glorious, revolutionary national triumph of democracy, applauded throughout most of the West, and at the same time practically abandoned by the world’s superpower, while the country’s territory is invaded by military force of a reactionary reborn Soviet-style empire.
Ukraine needs weapons, weapons, and weapons. Anti-aircraft weapons, anti-tank weapons. They are needed now, not after the next round of glorified sanctions following the imminent invasion of mainland Ukraine, when it will be too late, even if Russian invasion meets stiff resistance.