Ukraine finally has a green light to strike inside Russia using U.S. weapons — and it may have begun doing so.

A senior Ukrainian official hinted Monday that Kyiv had hit a missile system inside Russia using Western weapons, just days after many of Ukraine’s allies, including the United States, approved their limited use.

That followed months of pressure to ignore threats from the Kremlin and lift the restrictions, which Ukraine said had hampered its defensive effort. Even as President…