For some countries, harassing Russia has become a "new kind of sport," Russian President Vladimir Putin said in a speech on Wednesday.

Addressing Russian lawmakers and the nation at large, Putin said Moscow's response has been "reserved" and "without any irony, modest."

"We really don't want to burn any bridges, but if someone takes our good intentions for indifference or weakness, and if they intend to burn or destroy those bridges themselves, they should know that Russia's response would be asymmetrical, quick and tough," said the Kremlin chief.

What did Putin say about red lines?

Russia has enough "patience, responsibility, and common sense" Putin said, but warned against crossing "the red line."

"And where this line is, we will decide in any concrete case on our own," he added.

"The organizers of any provocations that threaten basic interests of our security will regret it like they haven't regretted anything in a long time."

According to deputy chairman of the State Duma Defense Committee Andrei Krasov, the Arctic, Ukraine, and the Baltic states are areas where Russia can mark "red lines." 

"But for the most part, the 'red lines' are probably the Arctic as well," Krasov told Russian news agency Interfax, stressing that the Arctic is Russian territory. 

Putin has said that the development of Russia's Arctic region is a priority as ice cover melts. Moscow has invested heavily in developing what it calls the Northern Sea Route.

The route is vital to Moscow, not only economically but also militarily and strategically. Russia also intends to use the route for exporting hydrocarbons to various parts of Asia. China, which has also used the Northern Sea Route for commercial purposes, has been sending an increasing number of vessels to Europe via the route since 2013.

Why was 'The Jungle Book' mentioned?

Putin's speech comes as the ties between Russia and the West are hitting a new low over the conflict in Ukraine, and the poisoning and imprisonment of Kremlin critic Alexei Navalny. In the latest diplomatic blow, the Czech Republic accused Russian secret services of being behind a 2014 blast in the Vrbetice ammunition depot.

The Russian president did not name Russia's adversaries abroad, but seemed to hint at the US and its allies with a comparison from "The Jungle Book" by Rudyard Kipling.

Putin spoke of the book's main antagonist, the tiger Shere Khan, and his underling Tabaqui, the jackal.

"There are all kinds of little Tabaquis hanging around Shere Khan," Putin said. "They are howling to appease their sovereign."

What about Navalny?

Putin spoke for well over an hour, focusing on the coronavirus pandemic and the vaccination drive, climate reforms, and internal social reforms in Russia. The 68-year-old ended his speech by pointing to Russia's advances in modernizing its military.

However, he did not address the ongoing protests demanding freedom for imprisoned opposition leader Alexei Navalny on Wednesday. The anti-corruption activist is currently engaged in a hunger strike and his health is said to be failing. Several top members of his team have been detained ahead of a Moscow rally planned for Wednesday afternoon.

Ignoring Navalny has been Putin's standard approach for many years, with the Russian president carefully avoiding uttering Navalny's name in public.

Later on Wednesday, hundreds of Navalny supporters were detained in planned protests in Moscow and other cities. According to the OVD-Info group monitoring the detentions, as many as 1,000 were detained by police nationwide.

European Parliament 'firm against Putin's aggression'

Navalny's doctors have warned he is at risk of dying. Navalny is demanding medical help from an independent civilian doctor.

Manfred Weber, leader of the centre-right bloc known as the European People's Party in the European Parliament, told DW that in the case Navalny does die in Russian custody, the German-Russian Nord Steam 2 pipeline "cannot be finished."

Weber said Putin "must know the price is high" and that he "must respect international obligations and rules," adding that Moscow's mass deployment of troops at th Ukraine border shows "a clear escalation."

According to EU top diplomat Josep Borrell, more than 100,000 Russian troops have massed on Ukraine's border and in annexed Crimea.