Ukraine's President Viktor Yushchenko has named a controversial ally as prime minister while seeking to patch up ties with Russia on a visit to Moscow.
Yushchenko (left) wants to reassure Ukraine's powerful neighbour
Mr Yushchenko held talks with Russian President Vladimir Putin, who had backed his bitter rival Viktor Yanukovych in the marathon election.
Mr Yushchenko's nominee, Yulia Tymoshenko, helped lead the "Orange Revolution" that secured his victory.
But correspondents say many Russians regard her views with deep suspicion.
Russia has been seeking the radical reformer's extradition on bribery charges.
Ukraine looks west
Hosting Mr Yushchenko in the Kremlin, Mr Putin said he was happy Ukraine's political turmoil was over.
There was a warm handshake and both leaders appeared anxious to show they were mending fences, the BBC's Sarah Rainsford reports.
Mr Yushchenko's Moscow visit on his first day in office will earn him favour in Kremlin, she says.
They held almost three hours of talks.
Mr Yushchenko said there was every reason for optimism that any problem with Russia could be solved.
For centuries Ukraine - on whose territory there was once a Slavic state from which Russia also claims its origins - has had close ties to Russia, still its biggest trade partner.
On Sunday Mr Yushchenko said Ukraine's future was in the EU. He will also tour Central and Western Europe this week.
Mr Yushchenko beat Mr Yanukovych in a re-run of November's disputed poll.
The 26 December repeat run-off was held after the Supreme Court ruled that the original vote - officially won by Mr Yanukovych - had been rigged.
Vast crowds thronged Kiev's Independence Square on Sunday
Independent election observers said the re-run had been much fairer than earlier rounds.
By making his first foreign visit to Moscow, Mr Yushchenko keeps a promise given at the height of Ukraine's longest-ever presidential campaign.
"We need to talk without delay and honestly," he told reporters in Ukraine at the time.
His camp complained about what it perceived as meddling by Mr Putin, who twice visited Ukraine during the campaign to show support for Mr Yanukovych.
"I really disliked the fact that Russia campaigned in favour of one candidate," Mr Yushchenko told the Russian daily Izvestia last month.
Mr Putin also angered Mr Yushchenko's backers by congratulating Mr Yanukovych with the victory in the original run-off without waiting for the final results to be announced.
Mr Yushchenko's Moscow visit is also seen as an attempt to placate Ukraine's predominantly Russian speaking south-eastern regions, where Mr Yanukovych enjoys strong backing, analysts say.
Mr Yushchenko's swearing-in on Sunday in the capital, Kiev, was watched by eight heads of state, along with US Secretary of State Colin Powell.
In contrast, Russia had relatively low-level representation - Sergei Mironov, the head of the upper house of parliament.