KYIV — Neil Young songs aren’t typically used as tools of diplomacy. Tuesday night in wartime Ukraine’s capital, not long before curfew, Secretary of State Antony Blinken deployed a left-handed guitar in the service of supporting Kyiv in its fight against Russia.

Before Blinken became the top American diplomat, he was a serious rock guitarist — and along with a Ukrainian band, he played “Rockin’ in the Free World,” a 1989 song by Young, the Canadian American musician, for a packed basement music club.