“The United States will stand with the international community in affirming that there will be costs for any military intervention in Ukraine.”

Is there any reason for Russia to think Mr. Obama means business? What were the costs to Russia for harboring Edward Snowden ? When the Kremlin was considering in June what to do with the fugitive NSA contractor living in a Moscow transit lounge, Mr. Kerry warned that there would be “consequences” for giving him asylum. He got asylum; there were no consequences.

Two months later, Mr. Obama was happy to accept Russian mediation for a face-saving deal on Syria’s chemical weapons rather than impose the consequences he had promised if Bashar Assad used them. A few months after that, the administration quietly eased its enforcement of the Magnitsky Act sanctioning corrupt Russian officials.

It’s probably asking too much of this president to see a connection between his Syria capitulation and this month’s events in Ukraine. But Republicans who contributed to last September’s fiasco might consider where their isolationist dalliance has led.