The United States is urging all Ukrainians, including those in rebel-controlled areas in the east as well as the illegally annexed Crimean peninsula, to vote in upcoming parliamentary elections.
State Department spokeswoman Jen Psaki called the weekend election "another milestone" for Ukraine.
Psaki said the United States would "strongly condemn any interference" in the election.
Pro-Russian rebels in the eastern regions of Donetsk and Luhansk are vowing to hold their own separate elections in November.
But Psaki said the "only legitimate elections" taking place in Ukraine are the parliamentary vote on October 26 and local council elections on December 7.
Psaki said Washington "stands ready to work with Ukraine's new parliament to fight corruption, promote reforms and pursue a peaceful resolution to the conflict in the east of the country."
Russia will recognize the results, President Vladimir Putin's chief of staff, Sergei Ivanov, told the Interfax news agency in Sochi on October 23.
Russia wants normality to return to Ukraine, he was quoted as saying.
However, Ukrainian Prime Minister Arseniy Yatsenyuk has warned Russia could try to disrupt the vote.
Yatsenyuk told a meeting of top security officials and election monitors on October 23 that it is "absolutely clear that attempts to destabilize the situation will continue and will be provoked by Russia."
Yatsenyuk said that "we are in a state of Russian aggression and we have before us one more challenge: to hold parliamentary elections."
The prime minister said Ukraine needs the "full mobilization of the entire law-enforcement system to prevent violations of the election process and attempts at terrorist acts during the elections."
Interior Minister Arsen Avakov said authorities have ordered some 82,000 police officers on duty for election day.
He said 4,000 members of a special reaction force would be among those maintaining order during polling hours and would be concentrated in "those precincts where there is a risk of some terrorist acts or aggressive actions by some...candidates."
The warning by Yatsenyuk comes on the heels of three violent attacks on parliamentary candidates in the past week.
The latest, against Volodymyr Borysenko, a member of Yatsenyuk's People's Front Party, occurred on October 20 when Borysenko was shot at and had an explosive thrown at him.
He reportedly only survived the attack because he was wearing body armor due to numerous death threats he had recently received.
Elections to the Verkhovna Rada, the parliament, will be held despite continued fighting in the eastern part of the country between Ukrainian government forces and pro-Russian separatists.
Voting will not take place in 14 districts of eastern Ukraine currently under the control of the separatists.
Those separatist-held areas -- in the Donetsk and Luhansk regions -- are planning on holding their own elections in November.
Additionally, Russia's illegal annexation of Crimea in March means the loss of 12 seats from the 450-seat parliament.
Polls show President Petro Poroshenko's party leading with some 30 percent of respondents saying they would cast their vote for the Petro Poroshenko Bloc.
A similar vote tally would mean Poroshenko's bloc would have a chance to form a coalition government, likely with nationalist groups who oppose conducting peace talks over fighting in the east.
Interfax quoted Poroshenko as saying in Odesa on October 23: "I'm sure that Ukraine will be sovereign and independent and nothing will threaten its territorial integrity. It won't be a frozen conflict because Donbas [a reference to the Donetsk and Luhansk areas where pro-Russian separatists maintain control of swaths of land] won't survive without Ukraine."
