Don't step over the line and re-militarize the Rhineland. Absorbing Austria would cross a red line. Breaking up Czechoslovakia is unacceptable. Get out of Poland by the announced deadline. The rest was history.
Don't dare blow up another American military barracks overseas. Don't ever consider another attack on the World Trade Center. Don't even try blowing up one more American embassy in East Africa. Don't ever put a hole in a U.S. warship again. The rest was history.
President Obama issued yet another one of those sorts of warnings to stop the violence to Ukrainian President Viktor Yanukovych just before protestors drove him out of office. "There will be consequences if people step over the line," Obama threatened.
Ben Rhodes, Obama's deputy national security adviser, amplified that veiled warning. He called the Ukrainian government repression "completely outrageous" -- as opposed to just outrageous or completely, completely outrageous.
Secretary of State John Kerry joined the chorus of condemnation by hinting at economic sanctions if Yanukovych didn't stop his violent crackdown on protestors.
Why does this rhetorical assault sound familiar?
Over the last five years, Obama has issued serial deadlines to Iran to cease and desist from its ongoing enrichment of uranium. All the while, more Iranian centrifuges went online.
Later, Obama turned from deadlines to red lines. He threatened Syrian President Bashar al-Assad with one about using chemical weapons. "A red line for us," the president warned, "is we start seeing a whole bunch of chemical weapons moving around or being utilized."
Assad moved over that American red line, using chemical weapons to gas his own people, and is now winning the war against the Syrian insurgents. In the end, an embarrassed Obama was reduced to denying that he had never issued a red line in the first place: "I didn't set a red line. The world set a red line."
The administration's latest cry of "outrageous" does not seem so absolute either. Remember, the president himself used that exact adjective to condemn the IRS scandal when it was revealed that the tax agency was inordinately focusing on conservative groups.
Later, after various key IRS officials had invoked the Fifth Amendment, resigned or abruptly retired, Obama brushed off the scandal. It was, he said, mostly a media event conjured up by "outraged" journalists. Somehow, a scandal that the president once decried as institutional abuse ended up as a media melodrama perpetrated by unduly outraged reporters.
Will the Ukrainian mess now abate due to Kerry's hints at sanctions?