In a frigid Moscow two years ago, I had one of my last encounters with Boris Nemtsov.

“Aren’t you afraid you’ll be put in jail, or something worse?” I asked.

“Pasha V.V. [that’s what they call Putin in Russia] won’t cross a certain line. He won’t target me physically. They have a rule to not touch former members of the government.”

Boris certainly qualified for that category. He was a successful and well-loved governor of Nizhny Novgorod between 1991 and 1997; he was a deputy prime minister for a year under Victor Chernomyrdin in 1998; he was a parliamentarian, and even a member of Russia’s Security Council.

With his move into the opposition, Nemtsov was no stranger to threats and intimidation. But the threats had gotten more serious lately, and Boris had said in recent interviews that the Putin regime might want to see him removed. Even his mother, as if she sensed that something terrible was about to happen, had been warning him about the dangers.

Well, we now know that every line is crossable in today’s Russia. Boris Nemtsov is the first opposition leader, who also happened to be a high-ranking former government official, to be murdered in cold blood. The other high-profile murders of the Putin years—Anna Politkovskaya, the dissident journalist, Alexander Litvinenko, the dissident FSB agent, and Sergei Magnitsky, the anti-corruption lawyer—had not been directly involved in politics. Even Sergei Yushenkov, the opposition leader killed in 2003 near his home, had never served at as high a level as Boris had.

The ‘immunity’ Boris was counting on was far from a fanciful concept. It represented an insurance policy for the present government, an important precedent Putin’s lieutenants could rely on in case the government ever fell—be it by coup, revolution or even by the peaceful democratic means Boris had always advocated. Nemtsov’s death thus means that the Russian authorities are no longer afraid of anything—and have no plans to relinquish power any time soon.

Boris Nemtsov’s assassination in Moscow’s center resembles something out of the times of Stalin’s Great Terror. The authorities’ reason for sanctioning the killing must not be made too mysterious to the people. The significance of the death must be clear to all, and his death must serve as a lesson. His bullet-ridden body plastered all across Russian newspapers yesterday was a warning: “Look, even a man like that cannot feel safe.” Nemtsov was one of those opposition leaders who visited the West often, who attended various conferences, acting like an informal foreign minister of this “other Russia”. Cynics used to say that talks held in hotel lobbies in Zurich don’t bother the Kremlin. Boris’ crumpled body, beamed into every television set across Russia yesterday, is a clear message to all opposition leaders, journalists and independent activists in Russia: “Don’t think that abroad you can say what you want. The authorities keep an eye on you whether you are in Warsaw or Washington. Enough is enough: time to choose sides.”

An important element of Boris Nemtsov’s quarrel with the Kremlin was his attitude towards the annexation of Crimea, and Russia’s policies in Ukraine more broadly. He rejected in the strongest terms the rationale proffered by the Kremlin for waging war against its neighbor and the attendant territorial plunder. Again, the message is unmistakeable: Nemtsov was murdered on the eve of the first anniversary of Crimea’s annexation.

Polonium was used to kill Litvinenko, although it would have been much easier to find another, less spectacular way to remove him. But then perhaps nobody would have paid attention to his death. That’s why Nemtsov had to die directly in the shadow of the Kremlin. A man whose phone is almost certainly wiretapped, whose every conversation is without doubt listened to 24/7—who pointedly organized his meetings in the city center knowing full well that his every movement is watched anyway—had to die spectacularly in the most secure part of town, literally watched over by hundreds of agents at all times. No matter who physically pulled the trigger, political responsibility for Friday night’s tragedy is clear. The complete brazenness of the act crosses yet another important line in today’s Russia.

In the Russian tradition, war is a sibling of terror, and both of them serve the purpose of consolidating power for the establishment. When you take a step back and look at recent history, a clear pattern of a different set of lines being crossed emerges: the wars in Chechnya (1994-96, 1999-2009) took place in the territory of Russian Federation; the war in Georgia (2008) was waged against a neighboring country; the war against Ukraine (since 2014) is an aggression towards a country associated with the European Union and one that was especially engaged in military cooperation with NATO. Buzzing the maritime borders of Sweden or Great Britain are signs that the borders of NATO and the EU are not inviolate for this administration. The troubling abduction of a soldier in Estonia late last year is the first physical evidence of crossing of lines representing the supposedly magical borders surrounding NATO countries. And it is unlikely to be the last.

After all, this is how it worked domestically: first in line were independent activists and journalists; then the rebellious special services officers and the disobedient lawyers; now the time has come for the politicians.

How to say goodbye to Boris? He was a cordial, warm, big-hearted and friendly man. He was brave. In Crimea’s case, he stood for international law and rules. He knew this would not only ruffle feathers inside the Kremlin, but would also upset a large part of Russian society that had recently been carried away by nationalistic fervor. Despite that, he was determined to preserve the honor of his homeland even at the price of temporary rejection by his compatriots. He was in Kiev on the Maidan, because he understood that the same sun of freedom should shine for everyone in the former Russian/Soviet empire.

Boris Nemtsov’s radiant smile will be remembered by all of his friends, and all who knew him. His hearty embrace won’t greet us in Moscow again.

The great Polish poet Adam Mickiewicz included a poem “To My Muscovite Friends” in his romantic drama “Dziady” (Forefathers’ Eve). These were our words aimed at those in Russia with whom we dreamed of big changes in the 19th Century. These were the words of a Pole for those Russians who had to pay with their lives for their disobedience towards the Tsar. It is a monument of friendship with another Russia.

Mickiewicz was writing of Kondraty Ryleyev, a poet condemned to the gallows by the Tsar Nicholas for participating in the Decembrist uprising.

We read Mickiewicz, we think of Nemtsov:

Do ye remember me? When musing traces
Friends’ deaths, and banishments and baffled schemes,
Ye also gather, and your foreign faces
Have right of citizenry in my dreams.

Where are ye now? Ryleyev’s noble shoulders
That once, I clasped, now by the Tsar’s decree
Hang on the gallows, where his honour moulders;
A curse on folk that murder prophecy!