Alexei Nikolsky / AP / RIA-Novosti Russian Prime Minister Vladimir Putin, right, and his Ukrainian counterpart Yulia Tymoshenko

Vladimir Putin, Russia's Prime Minister and former President, is not renowned for his love of literature. But on Sunday he gave Russian journalists an unexpected reading tip: the diaries of Anton Denikin, a commander in the White Army, which fought the Bolsheviks after the revolution in 1917. (See TIME's photos of last year's war in Georgia.)

"He has a discussion there about Big Russia and Little Russia  Ukraine," Russian news wires quoted Putin as saying after laying a wreath in Moscow at the grave of Denikin, who is now portrayed as a Russian patriot. "He says that no one should be allowed to interfere in relations between us; they have always been the business of Russia itself." (See TIME's Person of the Year: Vladimir Putin.)

Putin's words are seen as the latest in an ongoing volley of pointed warnings to the West not to meddle in Ukraine, which has such close historical and cultural ties to Russia that the Kremlin considers the country firmly within its sphere of interests.

"The Russian leadership is very apprehensive about what it sees as Western moves designed to tear Ukraine away from Russia," says Dmitry Trenin, director of the Carnegie Moscow Center, an independent think tank in Moscow. "Their central foreign policy goal is to create a power center around Russia. Any move by the West towards the former Soviet republics is seen as damaging Russia's interests."

Moscow has reacted angrily to Ukrainian President Viktor Yushchenko's attempts in recent years to gain NATO membership and to a recent agreement in March under which the European Union would help modernize Ukraine's aging gas-transport system. "This agreement is Exhibit A in Moscow's collection [of complaints]," says Trenin. "It's evidence that Europe is concluding bilateral deals with Ukraine that undermine Russia's interests."

Russian leaders have also expressed concerns about the E.U.'s Eastern Partnership program, which was unveiled earlier this month and aims to deepen economic and political ties with six former Soviet states, including Ukraine. At the E.U.-Russia summit in Khabarovsk over the weekend, Russian President Dmitri Medvedev said E.U. officials had "failed to persuade" him that it was not harmful to Russian interests. "What confuses me is that some states ... see this partnership as a partnership against Russia," he said.

Putin's reference on Sunday to "Little Russia"  a term used during the Russian Empire to describe parts of modern-day Ukraine that came under czarist rule  has raised hackles in Ukraine, where many consider it demeaning and offensive.

"These comments by Putin should be taken very seriously," says Olexandr Paliy, a political analyst with the Institute of Foreign Policy at the Ukrainian Ministry of Foreign Affairs' Diplomatic Academy. "Russia is engaged in a propaganda war against Ukraine, designed to convince the West not to support Ukraine. Russia doesn't understand cooperation with equals, only with subordinates."

Putin is not known for his tact when speaking of Russia's western neighbor, which declared independence from the Soviet Union in 1991. In April 2008, a source told Russia's Kommersant newspaper how Putin described Ukraine to George Bush at a NATO meeting in Bucharest: "You don't understand, George, that Ukraine is not even a state. What is Ukraine? Part of its territories is Eastern Europe, but the greater part is a gift from us."

Such rhetoric led to fears that after its army's foray into South Ossetia in August, Russia would turn its attention to Ukraine's Crimean peninsula, which has a predominantly ethnic Russian population and is home to Russia's Black Sea Fleet. In an article in Ukraine's Den newspaper on Thursday, Yuriy Shcherbak, Ukraine's former ambassador to the U.S., wrote that political analysts close to the Russian leadership were keen to portray Ukraine, which has huge economic woes and a political élite riven by infighting, as a "failed state."

"Aggressive conversations are taking place concerning Ukraine and the dividing of its territory ... at various levels of the Russian political, military and secret-service leadership," he wrote. In fact, other experts suggest, such belligerent talk is meant more as a corrective threat than a potential course of action. But even if Moscow has no immediate designs on Crimea, the continued flow of baleful utterances from the Kremlin does reflect a desire for what Medvedev has called Russia's "privileged interests" in the region to be respected  in terms of politics, business and culture.

And the Kremlin certainly has plenty of levers to pull in Ukraine to make its views felt, with its control over gas supplies, alongside the popularity of Russian state-controlled TV in the east and south of the country, where pro-Russian sentiment is strongest. "In certain sections of the Ukrainian political and business élite, there are links with Russia stretching back to Soviet times," says Paliy from the Institute of Foreign Policy. "There are also a large number of Russian-sponsored think tanks in Ukraine, which function freely and push the Kremlin's views."

These levers are likely to play a significant role in Ukraine's upcoming presidential elections, set for next January. Last time around, in 2004, Russia and Putin threw their weight behind then Prime Minister Viktor Yanukovych, whose initial victory was overturned after massive protests in Kiev against vote-rigging, which turned into the so-called Orange Revolution. This time, analysts say the Kremlin will probably diversify its approach, with support for both Yanukovych and previously hostile Prime Minister Yulia Tymoshenko, President Yushchenko's former Orange ally.

"The Russian leadership learnt one important lesson from 2004  not to put all their eggs in one basket," says Trenin. Meanwhile, Russians and Ukrainians alike will be watching for Putin's next trenchant explanation from literary history.

See TIME's photos of the Russian Czars.