A deal to end fighting in eastern Ukraine could be reached this week, Russian President Vladimir Putin has said.
Following a phone call with Ukrainian President Petro Poroshenko, Putin said their views on ending the violence were "very close" and suggested Kiev and the pro-Russian separatists could reach an agreement by Friday.
Earlier US President Barack Obama said a ceasefire would only succeed if Russia stopped sending troops "disguised as separatists" into Ukraine.
Russian President Vladimir Putin and his Ukrainian counterpart Petro Poroshenko have spoken by phone and "largely agree" on a possible way out of the Ukraine crisis, Interfax news agency reported, citing Putin's spokesman.
"The viewpoints of the presidents of the two countries largely coincide on possible ways out of the grave crisis situation," Dmitry Peskov was quoted as saying.
President Vladimir Putin said Moscow could not stand aside when people were being shot at in Ukraine, he told Russia's state TV Channel 1 in an interview.
It must be borne in mind that Russia cannot stand aside when people are being shot at almost at point blank.
Mr Putin also said ending the crisis was down to "the political will of the current Ukrainian authorities".
The West has accused Moscow of supporting pro-Russian separatists who are fighting Ukrainian government forces in the east of the country.
Russia president Vladimir Putin said it is impossible to say when the Ukraine crisis will end and it depended on the political will of Ukraine's leadership, according to Reuters citing RIA news agency.
President Vladimir Putin has said Russia will continue to provide humanitarian aid to civilians in eastern Ukraine, the Kremlin announced.
He is also reported to have ordered separatist rebels to provide a humanitarian corridor for encircled Ukrainian troops to exit.
Russian President Vladimir Putin has reportedly told German Chancellor Angela Merkel that he decided to send a humanitarian aid convoy into Ukraine because he could no longer wait.
According to the Kremlin account of the phone call, President Putin expressed "serious concern" about the military escalation in eastern Ukraine.
Russian President Vladimir Putin has told his government to prepare for retaliatory measures against the latest western sanctions, the Tass News Agency reports.
"Of course, it should be done carefully in order to support domestic producers and not hamper consumers," he was quoted as saying.
Russian President Vladimir Putin has accused the West of bullying him over the Ukraine crisis - an approach he called both "strange and unacceptable".
European foreign ministers in Brussels have drawn up new sanctions against Russia but not the economic measures supported by Britain and the US.
ITV News Diplomatic Correspondent John Ray reports from Moscow:
Russian president Vladimir Putin has urged Britain to "negotiate" the sovereignty of the Falklands Islands with Argentina, accusing the UK of a "double standard in foreign relations."
Speaking at an official dinner during a visit to Buenos Aires, Putin said: "Russia supports the need to find a solution in the dispute for the [Falkland] Islands at the negotiation table directly between Great Britain and Argentina.
"I wanted to bring attention to the words of Mrs President [Fernandez] regarding the double standard in foreign relations."
Argentina president Cristina Fernandez de Kirchner has previously accused Britain of hypocrisy in criticising Crimea's pro-Russian referendum vote yet supporting a pro-British vote in the Falklands.
She said: "I appreciate, of course, the support for our national cause [sovereignty of the Falkland Islands] which is not a uniquely Argentine cause."
Russian President Vladimir Putin discussed proposals for peace in Ukraine with the US President Barack Obama today, the Kremlin said in a statement.
Speaking on the phone, the two leaders discussed the Ukrainian military ceasefire that was declared by President Petro Poroshenko last week.
Mr Obama urged Mr Putin to support the peace plan and said Moscow would face further "costs" if it did not take steps to reduce tensions in the country, the White House said.