Vladimir putin signs crimea treaty
US imposes sanctions on 'Putin's bridge' to Crimea
The US Department of the Treasury added dozens of people and companies to the list.
The European leaders urged Russia to do more to end constant, deadly violations of a ceasefire.
Petro Poroshenko told a televised meeting of the government a ceasefire was proving difficult to maintain.
A summit of EU leaders is meeting in Brussels.
NATO said Russia had increased its forces along the border and now had around 12,000 troops in the area.
Three-way talks involving pro-Moscow rebels aim to pave the way for a new ceasefire.
The announcement came after a four-way phone call with Vladimir Putin and German and French leaders.
The suggestion is viewed as necessary to prevent militants and arms entering Ukraine.
French President Francois Hollande will be joined at the commemorations by 20 foreign leaders.
Some Tatars fear a return to Stalinist repression despite official promises to respect their rights.
This is the heaviest loss of life for government forces in a single clash.
Pro-Moscow separatists in eastern Ukraine ignored Putin’s public call to delay a referendum on self-vote.
Ukraine said the Odessa force would replace local police who had failed to tackle rebel actions.
Ukrainian forces launched an operation to retake the eastern town of Slaviansk on Thursday.
Pro-Russian separatists attacked a base of the Ukrainian National Guard in an eastern city overnight.
Kiev is seeking to reassert control slowly and without bloodshed before Thursday’s meeting.
Ukraine’s security said separatists occupying the security headquarters had planted bombs in the building.
Sentletse Diakanyo says the Western pursuit of economic interests is relentless.
The Ukrainian government denounced the visit as a violation of the rules of diplomacy.