On Wednesday, Russian President Vladimir Putin hinted that he may escalate his military pressure against Ukraine.

Asked about the British deployment last week of its HMS Defender destroyer within 12 nautical miles of Russian-occupied Crimea, Putin said that the Defender had been joined by a U.S. surveillance aircraft. He even provided what he said was that aircraft’s tail number. Lamenting this U.S.-British “provocation” in the context of what he said was Russia’s greater respect for Western borders, Putin argued that his “more fundamental” concern rests with foreign military bases on Ukraine’s territory. Putin appears to be referring to a U.S.-led military training center at Yavoriv, in far-western Ukraine.