To Putin, NATO advisors and equipment are gradually transforming Ukraine into a de facto satellite of the Western alliance. He’s not entirely wrong.

Russia experts believe he probably doesn’t want to invade all of Ukraine — a move that would be costly in military, economic and diplomatic terms — so much as he wants to stop the country’s westward drift.

“Putin doesn’t want Ukraine to have any interaction whatever with NATO,” Fiona Hill, a National Security Council official during the Trump administration, told me last week. “He wants Ukraine to be entirely, irrevocably neutral.”

“He’s testing us,” Hill added. “He’s waiting to see how everyone reacts. If there’s a strong enough reaction, he may back off. The softer our response, the more likely he will go.”