KIEV, Ukraine — The standoff between Ukrainians who want European-style democracy and a government that is aligned with Russia erupted Tuesday in an explosion of violence that left 25 dead and could reignite an East-West confrontation thought long buried.
The U.S. State Department issued a travel advisory Tuesday warning that "U.S. citizens are urged to maintain a low profile and to remain indoors at night while clashes continue.''
The Ukrainian Health Ministry reports 241 have been hospitalized.
Thousands of police armed with stun grenades and water cannons rushed at protesters in a camp in Ukraine's capital after weeks of calm in which the two sides appeared to be on the verge of a compromise.
But the Ukraine Parliament's refusal Tuesday to vote on a bill to restore a 2004 constitution limiting the powers of President Viktor Yanukovych enraged anti-government protesters, who've been occupying the streets for weeks.
Marching toward the Parliament, they were halted by police in riot gear who also have been in the streets for for weeks, standing guard. No one knows who fired first, but by evening's end 20 Ukrainians lay dead and thousands more were injured, said Oleh Musiy, coordinator of medical services.
"The risk here is tremendous, because Ukraine is an industrial powerhouse in a strategic location," says Ariel Cohen, a Russia analyst at the Heritage Foundation who says this country of 50 million is on the verge of civil war.
In Washington, State Department spokeswoman Jen Psaki said the administration urges the Ukraine government "to de-escalate the situation immediately and resume dialogue with the opposition on a peaceful path forward. ''
Ukraine's industrial might — producing everything from food to aircraft — mean its markets will be a major influence on Europe's economic future. But its role as a strategic buffer between Europe and Russia, at a time when President Vladimir Putin seeks to regain dominance over republics Russia once controlled means it could be a powerful ally to the United States or an adversary.
"This is crazy, it's like a real war — they are going to kill each other," said protester Liudmila Mazur, 50, as she watched protesters attack a police barricade that blocked the way to Parliament.
"I don't know if there is another way now as the government understands only force," she added. "When we were protesting peacefully, they didn't hear us."
The leaders of the protesters said the melee ends all desire for a compromise with the government. They threatened to bring hundreds of thousands into the streets, and are pleading with the United States and Europe to confront Moscow over what they say is a usurpation of their fledgling democracy orchestrated by Putin.
Opposition leader Vitali Klitschko said that Yanukovych agreed to meet with opposition leaders early Wednesday, but it may be too late.
"All the world is watching Ukraine," Klitschko said. "I can't imagine working with Yanukovych's government now."
He called on Yanukovych to agree to the reforms and call an early election, or face a serious escalation of the crisis.
"We are talking minutes, not hours," Klitschko told reporters.
Ukraine has been struggling to maintain its independence and unity since it broke away in 1991 from the Soviet Union, the former Communist superpower that dissolved in an uprising of its own.
It was one of several republics subsumed by the USSR during its nearly seven-decade existence, in which is installed puppet regimes in captive nations that included much of Eastern Europe.
But Ukraine is by far the largest, the second-largest country land-wise in Europe besides Russia.
In the breakup, Ukraine agreed to give up the nuclear arsenal the Soviets based there during the Cold War, in which U.S.-backed Western Europe pressed for freedom behind the Iron Curtain, where nations such as Poland, Bulgaria, Estonia and East Germany were strangled by repression and stagnation.
At the time, Ukraine looked to NATO for protection, but was denied admission out of concern for provoking Russia, then undergoing attempts to democratize. The fault lines soon became apparent in Ukraine.
Russian is spoken in the eastern and southern regions of the country, where economic and cultural ties with Moscow are strong. But western Ukraine, where the independence movement was born, wanted closer ties to the 28-nation European Union.
The ascension to power of Putin, a former officer in the Soviet secret service who called the demise of the despotic USSR the "greatest geopolitical catastrophe of the century," only pushed western Ukraine to press even harder to escape from from Moscow's orbit.
Putin expressly urged his country to regain influence over what was lost, and he acted on it in 2008 in Georgia when he sent in Russian troops to put down what he said was an attempt by the elected government to marginalize Russian-speaking citizens there. The troops remain, and the message was received.
Then came what anti-Russian Ukrainians felt was going to be a major shift toward Europe and away from Russia, a far-reaching trade pact that would have tied Ukraine's economic future toward free markets with the EU.
Tens of thousands of Ukrainians protested peacefully for the pact, and in November the government violently dispersed them from the center of the capital. They returned with hundreds of thousands to press for a deal that Yanukovych had once vowed to sign.
But in December, he suddenly called off the signing ceremony and appeared in Moscow, where he announced he was instead going to join a trade union with Russia in return for $15 billion in loans and cut-rate gas.
Protesters took over buildings in several cities, including Kiev city hall. After initial clashes and arrests, the two sides hunkered down, at the urging of the EU and USA. Sen. John McCain, R-Ariz., who stood with protesters in Kiev, urged the Obama administration to press Moscow to stay out.
Moscow suspended its payments; the government released of scores of jailed activists. Over the weekend, protesters vacated buildings in return for a vote on measures that would strengthen democratic institutions.
But Putin had issued warnings that he may have to intervene in events more strongly in Ukraine, and on Monday, while opposition leaders were meeting with German Chancellor Angela Merkel, he offered billions of new dollars to keep Ukraine's ailing economy going.
Word got out that Yanukovych was expected to nominate a new prime minister that the opposition was sure would be a Russian-leaning loyalist.
On Tuesday, the Parliament refused to take a vote on the pro-democracy measures, and the protesters camped in the streets marched straight at the phalanx of armed police.
Moving into Independence Square, which has been the center of nearly three months of protests, police dismantled some of the barricades and many of the protesters' tents were set on fire. Flames raged in the night but the protesters refused to run.
About 20,000 demonstrators fought with rocks, bats and fire bombs, singing the Ukrainian national anthem all the while. The Interior Ministry reported that seven police officers were among the dead.
EU foreign policy chief Catherine Ashton said she was "deeply worried" by the violence and urged politicians to "address the root causes." Russia blamed the upsurge on "connivance by Western politicians and European structures" and their refusal to consider the "aggressive actions" of radical factions within the protest movement.
U.S. Ambassador Geoffrey Payatt called for dialogue, but also threatened both sides with sanctions.
"We believe Ukraine's crisis can still be solved via dialogue, but those on both sides who fuel violence will open themselves to sanctions," Payatt said on Twitter.
U.S. policy for the past 25 years has been to support the sovereignty of former Soviet republics. A 1994 agreement between Ukraine and the USA guarantees Ukraine security but only from outside attack.
"We need to make clear to Russia that any kind of meddling in Ukraine internal affairs is totally unacceptable," said Cohen of the Heritage Foundation. "Ukraine is a sovereign country, despite what some in Russia may think."
Cohen says the Obama administration is looking to Russia to help tamp down violence in Syria and possibly help curtail Iran's nuclear program, so it may consider Ukraine a distraction.
The White House responded to the violence with a statement from Vice President Biden, who called on Yanukovych to pull back government forces and engage in a dialogue with his people. There was no mention of Russia.
Into the night, the pop of grenades could be heard here, and clouds of tear gas and smoke from burning cars and trucks filled the streets. Ukrainian authorities issued an ultimatum threatening "severe measures" or the government "will be obliged to restore order by any legal means."
"Emergency services all are filled to the brink — there is nowhere to put people up," Iryna Herashchenko, a member of Parliament with the opposition Ukrainian Democratic Alliance for Reform party, told Kiev Post.
Justice Minister Olena Lukash, a close Yanukovych aide, accused the opposition of violating earlier agreements with the government and blamed protest leaders for the violence.
But after the shocking battle between Ukrainians, the government sought calm.
"Negotiations can only happen when the opposition takes armed people off the streets and when calm is restored," presidential adviser Hanna Herman told RFE/RL broadcaster. "What the opposition is doing now, calling further for armed conflict, is a great crime against the Ukrainian people and the Ukrainian state."
Opposition leader Arseni Jazenjuk said there can be no calm because of the stakes for the country.
"This is the most dramatic period in the history of Ukraine since independence," Jazenjuk said. "The Ukrainian people are fighting for their freedom and liberty and we will fight until victory."
Klitschko said it is in the interest of the European Union and the European states that Ukraine is politically and economically stable: "because instability in Ukraine could lead to instability in the entire region." Jazenjuk described Yanukovych as a man trying to buy time with "never-ending negotiations."
"It is a turning point in the history of EuroMaidan," said Taras Berezovets, political analyst and head of Berta Communications in Kiev, referring to the name adopted by the protest movement.
"For sure, these events (today) were planned and initiated by the government encouraged by Kremlin. If the protest is dispersed, hundreds or even thousands of activists will be arrested, including opposition lawmakers.
"But in term of resources Yanukovych has lost," he added. "The question is, how long will his agony last and how many people he will bring down with him."
Contributing: Luigi Serenelli in Kiev, Jabeen Bhatti in Berlin, Oren Dorell in Washington, The Associated Press