WASHINGTON — The president orders his military into action in a war-torn country to protect a vulnerable population, authorizing strikes in service of a humanitarian mission. That was President Obama on Thursday. But it could be President Vladimir V. Putin of Russia in the not-too-distant future.

Never mind the deep differences between the wars consuming Iraq and Ukraine. If Mr. Putin ultimately decides to send Russian armed forces across the border, analysts say he now has one more pretext. Just as Mr. Obama says he is trying to protect Yazidis and Kurds threatened by Sunni Muslim extremists, Mr. Putin may argue he wants to protect Russian speakers from Ukrainian fascists.

“This could provide another justification — he could just throw it back at us,” said Fiona Hill, a scholar at the Brookings Institution and former American government intelligence officer on Russia who helped write “Mr. Putin,” a book on the Russian leader. “Whether this is the excuse he needs or not is another question. But is this an excuse he may use? Absolutely. It just adds more fuel to his fire if he wants one.”

Like others inside and outside government in Washington, Ms. Hill said she did not think Mr. Putin actually needed a pretext if he opted to invade because the factors driving his decision-making were long established. But the latest American military venture into Iraq may provide a talking point that would allow him to draw what analysts call a false equivalence and force the Obama administration to defend itself and argue why one intervention is legitimate and the other is not.