18 February saw another escalation of the violence
Violence has erupted in the Ukrainian capital Kiev once again, with several people being killed during clashes between anti-government protesters and police.
The stand-off, which has oscillated between calm and violence for months, escalated dramatically with reports of policemen being shot, and riot police moving in apparently to clear the peaceful protest camp on Independence Square.
The protests broke out after the government rejected a far-reaching accord with the European Union in favour of stronger ties with Russia in November 2013.
But they are now clearly directed at President Viktor Yanukovych.
How bad has the violence been?
Independence Square has at times resembled a war zone
Tuesday 18 February has been the bloodiest day so far. Clashes erupted outside parliament as opposition MPs complained they had been barred from introducing proposed constitutional changes to reduce the powers of President Yanukovych.
Before that, the scenes overnight on 19 and 20 January were some of the worst in nearly two months of demonstrations, with protesters torching police buses and hurling paving stones and petrol bombs. Police responded with tear gas, rubber bullets and water cannon.
Two people were shot dead at the site of the Kiev protest camp on Independence Square on 22 January. Another was found dead with torture marks in a forest near the capital. On 25 January a fourth protester was said to have died from injuries sustained in earlier violence.
The interior ministry reported on 28 January that one of three policemen stabbed by protesters in the southern city of Kherson had died.
Hundreds of protesters and police officers have been injured in the unrest. In one of the most disturbing developments, a protest leader Dmytro Bulatov emerged with serious facial injuries, saying he had been abducted, tortured for eight days and left for dead.
Protests have spread to a number of Ukrainian cities, mostly in the west of the country but also in Mr Yanukovych’s traditional support base in the east.
Hundreds of protesters have been arrested since the disturbances began.
What caused the protests?
The pro-EU rallies in Kiev in December drew crowds of some 200,000
The anti-protest laws certainly raised passion among the protesters. They had prescribed jail terms for anyone blockading public buildings and banned the wearing of masks or helmets at demonstrations.
But the original trigger for the protests was President Yanukovych’s decision not to sign a major partnership deal with the EU, despite years of negotiations aimed at integrating Ukraine with the 28-nation bloc.
Thousands of pro-EU Ukrainians poured on to the streets of the capital, urging President Yanukovych to cancel his U-turn and go ahead with the EU deal after all. He refused, and the protests continued.
When riot police first took action on 30 November, the images of them breaking up a student protest and leaving dozens of people injured only fuelled anger with the president and boosted the crowds in Independence Square.
The authorities sought to defuse the anger through measures such as the suspension of the mayor of Kiev and the release of detainees.
On 17 December, Russia and Ukraine announced a major deal under which Russia would buy $15bn-worth (£9.2bn; 10.9bn euros) of Ukrainian government bonds and slash the price of Russian gas sold to Ukraine.
The deal appeared to take the wind out of the sails of the protest movement but when a pro-opposition journalist, Tetyana Chornovol, was beaten up by unknown assailants on 25 December, there was a renewed outcry.
Who are the protesters?
Vitali Klitschko, with raised fist, hopes to become president in 2015
There are a number of main actors behind the rallies.
The protesters are mainly from the Kiev area and western Ukraine, where there is a greater affinity with the EU, rather than in the Russian-speaking east and south – though they include eastern Ukrainians too.
Vitali Klitschko, the former world heavyweight boxing champion and leader of the Udar (Punch) movement, has been a prominent demonstrator. He is very pro-EU and plans to run for president in 2015.
Arseniy Yatsenyuk, parliamentary leader of the country’s second biggest party, Fatherland, is an ally of Yulia Tymoshenko, the former prime minister who is now in prison.
The far-right group Svoboda (Freedom) is also involved. Led by Oleh Tyahnybok (pictured second from left), it stirred unease on New Year’s Day with a torch-lit procession through Kiev.
Other radical right-wingers include Bratstvo (Brotherhood) and Right Sector.
How has the West reacted?
The US embassy in Kiev revoked the visas of “several Ukrainians who were linked to the violence” after the deaths on 22 January.
EU leaders expressed shock at the deaths and called on all sides to halt the violence. Jose Manuel Barroso, president of the EU Commission, warned that the EU’s relationship with Ukraine might have to be reviewed.
The EU’s official position on the agreement abandoned in November is that the door remains open for Ukraine to sign but it has put any new negotiations on hold until there is a clear commitment to do so.
Both the EU and US condemned the now-revoked anti-protest laws, saying they were incompatible with Ukrainians’ democratic aspirations.
The EU and US have raised the prospect of a joint economic plan to help Ukraine bring an end to its crisis. But officials say any proposal would be linked to precise political and economic reforms and are adamant there will be no “bidding competition” with Russia.
Top EU diplomat Catherine Ashton has visited Kiev and is playing a key role in negotiating with the Ukrainian government and opposition.
On 6 February, a bugged phone conversation surfaced on the internet – purportedly between visiting Assistant Secretary of State Victoria Nuland and the US ambassador – revealing US thinking on key opposition figures. Ms Nuland was also apparently heard to use an expletive to describe the EU’s role in Ukraine.
Pictures of Tymoshenko have been prominent at the rallies in Kiev
Is Russia pulling the strings in Kiev?
The gas deal was announced after nearly four weeks of street protests in Ukraine
To many observers, the deal struck between Russia and Ukraine on 17 December points to a carrot-and-stick approach by the Kremlin.
The 2004 Orange Revolution led to Mr Yanukovych’s removal from power after his election was judged to have been fraudulent. Russia backed him then – and backs him now.
For centuries Ukraine was controlled by Moscow and many Russians see Ukraine as vital to Russian interests.
After the riots erupted on 19 January, Russian Foreign Minister SergeiLavrov warned the protests were “getting out of control”, and accused European politicians of stirring up the trouble.