Correction: An earlier version of the article incorrectly said that Ukraine was a satellite of the Soviet Union. It was part of the Soviet Union. This version has been corrected.

Crimean ethnic Tatars protest on the roadside in the settlement of Kok-Asan with a banner reading “No war!” as Russian troops move toward Simferopol on Ukraine’s Crimean Peninsula.

March 8, 2014 Crimean ethnic Tatars protest on the roadside in the settlement of Kok-Asan with a banner reading “No war!” as Russian troops move toward Simferopol on Ukraine’s Crimean Peninsula. Denis Sinyakov/European Pressphoto Agency

Russian troops and pro-Russian militants take up positions around the Crimean Peninsula in Ukraine, surrounding government buildings and military installations.

Russian troops and pro-Russian militants take up positions around the Crimean Peninsula in Ukraine, surrounding government buildings and military installations.

Russian troops and pro-Russian militants take up positions around the Crimean Peninsula in Ukraine, surrounding government buildings and military installations.

Pro-Russian lawmakers in the Black Sea peninsula of Crimea sparked a showdown reminiscent of the Cold War on Thursday, accelerating their bid to leave Ukraine and join Russia in a move that President Obama, the new government in Kiev and European leaders described as provocative and illegal.

Lawmakers in the autonomous region voted Thursday to join the Russian Federation and hold a referendum March 16 to validate the decision.

The regional parliament — now led by Sergei Aksyonov, a businessman and politician known around Kiev as the “Goblin” because of his alleged ties to organized crime — said it would nationalize Ukrainian state industries and begin setting up government ministries separate from Ukraine, which Crimea joined in 1954 when the nation was still a part of the Soviet Union.

“This is our response to the disorder and lawlessness in Kiev,” Sergei Shuvainikov, a member of the Crimean legislature, said Thursday. “We will decide our future ourselves.”

In Washington, Obama said the world was “well beyond the days when borders can be redrawn over the heads of democratic leaders,” as his administration imposed sanctions on Russians and Ukrainians involved in Russia’s military intervention in Crimea.

Speaking from the White House on Thursday, President Obama called “unconstitutional” a planned referendum in the Crimea over whether people there want to remain part of Ukraine, and reiterated a series of steps Russian President Vladimir Putin could take to “de-escalate” the conflict in the region. (The Associated Press)

European leaders also sounded alarms, denouncing the referendum plans as unacceptable.

British Prime Minister David Cameron told reporters after an emergency summit called by the 28-member European Union that if talks between Russia and Ukraine didn’t progress quickly, “asset freezes, travel bans, those things mentioned by the Americans, will be very firmly on the agenda.”

It remained unclear whether Thursday’s moves in Crimea were part of Russia’s precise calculations. But the extent of Moscow’s grip on the largely ethnic-

Russian region suggested that separatist leaders here were coordinating their actions with Russia, said Cliff Kupchan, head of the Russia and Eurasian team at the Eurasia Group, a Washington-based political and business consultancy.

“Russian troops are all over the place,” he said. “An ethnic-

Russian leader is calling the shots in Crimea. Could there be a smidgen of spontaneity in his actions? Yes. Is it credible that he is acting without coordinating with Moscow? I don’t find that credible.”

In any case, Russia’s parliament, the Duma, said Thursday that it would begin debating bills aimed at simplifying legislation to allow Crimea’s accession to Russia after the referendum and a decision by Russia’s leadership on the matter.

In Kiev, Ukrainian officials called for dialogue with Crimea’s lawmakers even while denouncing their moves.

“This is an illegitimate decision, and this so-called referendum has no legal grounds at all,” Ukrainian Prime Minister Arseniy Yatsenyuk told reporters in Brussels, where he met with E.U. leaders. “That’s the reason why we urge the Russian government not to support those who claim separatism in Ukraine.”

View Graphic See the Ukrainian crisis in detailed maps

‘There is no other option’

The pro-Russian lawmakers, who took control of the Crimean parliament last month, had already called for a March 30 referendum on the region’s future. But the moves Thursday marked not only an acceleration of the vote but a far more robust declaration of secession from Ukraine, where months of protests led to the ouster of pro-Russian President Viktor Yanukovych last month.

The coming vote raised the prospect of violence among those who want to remain part of Ukraine, particularly the region’s ethnic Tatars. Observers also said that they had little confidence that the referendum would be fair.

The declaration Thursday, however, was wildly popular among the ethnic Russians who make up the majority on the Crimean Peninsula. Store and road signs in the region are almost exclusively in Russian, not Ukrainian. Russian flags are flown from far more rooftops than are Ukrainian flags. School classes are taught in Russian, and it is the language most commonly spoken on the streets. Many residents say they do not understand a word of Ukrainian.

At a square in front of Sevastopol’s City Hall, where a sign saying “Kiev doesn’t tell us what to do” was taped to a front column, people wearing ribbons in the red, white and blue stripes of the Russian flag said they hate pro-Western Ukrainians, Obama and America equally.

“Of course, everyone will vote to be part of Russia, because we are Russian people,” said a woman carrying a small pennant bearing a likeness of Russian President Vladimir Putin. “We want it tomorrow.” She refused to give her name, saying she does not trust Americans.

Several people said they were ethnic Ukrainians but had lived for a long time in Crimea and were prepared to vote in favor of joining Russia.

“Sevastopol. Crimea. Russia. There is no other option,” said Leonid Klemenko, 72, a retired watch repairman.

The head of the Tatars in Crimea urged people to boycott the referendum, regardless of their ethnicity.

But in a place that looks like a craggy Mediterranean version of Russia, many had a sense that a vote to break away from Ukraine is inevitable.

“Why postpone it?” said Vladimir Galichnikov, a 27-year-old security guard. “The economy will be better under Russia. Russia has a better army. Everything’s going to be better with Russia.”

Tensions rise in some spots

Although many residents in Crimea went about their business as usual, strolling in parks, dining in restaurants and attending concerts and art exhibits, tensions ratcheted up noticeably in a few locations.

On Wednesday, soldiers without insignia did not impede navy wives, curious neighbors, priests and journalists from approaching three Ukrainian ships in the Sevastopol harbor whose sailors have resisted demands to switch allegiances. But Thursday, men wearing an assortment of camouflage uniforms formed a cordon and turned away everyone who tried to get closer.

At one spot near the port where families have flocked to glimpse the sailors, about two dozen men stood in a tight line behind a personnel carrier bearing Russian plates. One man in the group said they were with a self-defense unit.

Russian forces continued to harass the Ukrainian military, although in some areas, they appeared to be changing tactics. The commander of the Belbek military base near Sevastopol said Russian forces blockading part of the Ukrainian installation have abandoned ultimatums and are offering apartments to those who pledge allegiance to Crimea.

Col. Yuli Mamchur met for several hours with representatives of the blockading troops and gained permission to send someone to the airfield to inspect planes damaged during the standoff, which began this week. He said both the Ukrainian military and the Russians are now in control of the base.

Mamchur said the Russians offered to provide apartments to about 350 people who work on the base and lack adequate housing.

“They have changed their tactics,” he told reporters after the talks concluded. “Before, they made ultimatums. Now, they offer apartments.”

He said none of the Ukrainian military personnel had defected yet.

Faiola reported from Kiev. Kathy Lally and Isabel Gorst in Moscow contributed to this report.