Sometime in the afternoon or evening of January 9, three Kurdish activists were assassinated in their office in Paris, France. To enter the office required being buzzed in and the office was not marked by signs. This was no random mugging or robbery: Whoever entered and shot dead Sakine Cansiz, a co-founder of the Kurdistan Workers Party (PKK); Fidan Doğan, a representative of the Brussels-based Kurdistan National Congress; and Leyla Söylemez was deliberate. French Interior Minister Manuel Valls visited the site of the murders and called the slaughter “intolerable.”

There are two main suspects: Turkey and Iran. Many Kurds are pointing the finger at Ankara. After all, Prime Minister Recep Tayyip Erdoğan feigns moderation toward the Kurds only when it suits him, but embraces a hardline approach when he wants to whip up Turkish nationalists. In recent years, the PKK has been winning its insurgency: The Turkish army has effectively lost control of much territory which the PKK now administers in far southeastern Anatolia.

A more likely suspect is Iran. Not only is there precedent—the Iranian regime assassinated Kurdish leaders in Vienna on July 13, 1989, just a month after Ayatollah Khomeini’s death. European diplomats dismissed that attack as a rogue event. It wasn’t: As I discuss in this article, one of the hit men was a Qods Force colonel who returned to Iran and received his first star as brigadier general. In 1992, German foreign minister Klaus Kinkel proposed a critical dialogue with Iran. The Qods Force responded by ordering a hit on Kurdish dissidents at a Berlin café. There is a clear pattern: When anyone reaches out their hand and asks the Iranian government to unclench their fist, the Iranian leadership sees not conciliation but a sign of weakness to exploit.

Why would the Iranians, however, go after Turkish Kurds? According to this report from the Iran Human Rights Documentation Center, Tehran’s fear of Kurdish separatism has increased tremendously since the fraudulent 2009 election. There is no doubt that Kurdish nationalists, including those based in Turkey, have strong links with their Iranian brethren. One of the reasons why the Iranian government supported militias in Iraq was not only to target American soldiers, but also Iraqi Kurdish federalists in Kirkuk and other disputed areas: The logic, as the Iraqi Kurds explained to me, went something like this: If Iraqi Kurdistan wins strong federalism with oil-rich Kirkuk included, then the potential blowback among Iranian Kurds could be great. If Shi’ite militias could disrupt that Iraqi Kurdish federalism, so much the better.

There is also precedent when it comes to Paris: French authorities already blame Iranian hit men for 11 assassinations of dissidents since Iran’s revolution. What’s one more?

There should be a cautionary lesson for the Obama administration, Senator Kerry, and perhaps Senator Hagel and John Brennan: Reaching out to Iran often sparks the worst aspects of Iranian regime behavior. It may sound counterintuitive, but the historical pattern is clear.