Petro Poroshenko agreed in August to take a lie detector test but said he did not trust that investigators would be unbiased.
"It is too early to talk about President Putin's offering his congratulations to Zelensky, as well as speaking about the possibilities of working together," a Kremlin spokesperson said about comedian-actor Volodymyr Zelensky, Ukraine's new president.
"This is just a first step towards a great victory," said presidential candidate Volodymyr Zelenskiy.
Ukraine sanctioned 848 people and 294 entities on Wednesday.
Russia's top diplomat described the NATO alliance as a bully working to spread its influence across the Balkans.
"We know that we can only solve things through being reasonable and through dialogue," the German chancellor said.
The S-400 system is considered the most advanced in the world.
The men were captured during a violent confrontation with Russian navy ships on Sunday.
Angry anti-Russian demonstrators set fires and threw smoke bombs and flares outside the compound.
Ukraine's president called for officials to draft an formal claim, as recent estimates from Kiev suggest the bill could exceed $50 billion.
Since Russia's annexation of Crimea in 2014, the question of where Ukrainians go to worship has become a political issue.
The Javelin missiles are deemed so effective that intention to sell or deploy them has long warranted a big political announcement.
It is the second time the Roshen store has been targeted in protest against Petro Poroshenko.
President Petro Poroshenko arrives in Washington, vowing to help Trump avoid "injustice" from Putin.
The German Chancellor will discuss the situation in east Ukraine.
Russian parliamentary elections in Crimea are "unacceptable" claims Danish minister.
East Ukraine has seen an uptick in violence and casualties in recent weeks.
Kiev says FSB agents and Russian armed forces shot at each other.
The opposition Radical Party warned Poroshenko may be a bad luck charm for the team.
Parliament member Nadiya Savchenko was active during the 2014 Maidan revolution, and some think she will become an agent of change in Ukraine's parliament.
The parliament-government stalemate ends with new PM, the president said.