Ukrainian officials are also working to hold another round of unity talks in eastern Ukraine in the coming days, US Secretary of State John Kerry said after talks in London.
“Pro-Russian separatists and their supporters are literally sowing mayhem in communities like Slavyansk,” Kerry said.
“Far from defending the rights of the people in the east they are seeking to speak for everybody through the barrel of the gun,” he told reporters.
Ukraine is due to hold crunch presidential elections on May 25, following the ouster of Ukraine’s pro-Russian leader Viktor Yanukovych in February.
In a meeting with his French, German, British and Italian counterparts in London “we agreed.. that if Russia or its proxies disrupt the elections the United States and those countries represented here today in European Union will impose sectoral economic sanctions as a results,” the top US diplomat said.
“Our message is really, quite simple: ‘Let Ukraine vote. Let the Ukrainian people choose their future.'”
British Foreign Secretary William Hague said: “We all agreed that Russia’s behaviour towards the elections will determine whether or not wider economic and trade sanctions will be applied by the United States and by the European Union.”
They agreed to continue “preparations for these sanctions, while of course urging Russia to stop any actions that prevent the elections going ahead peacefully,” Hague added.
US President Barack Obama has already drafted an executive order to impose sanctions on Russia across key sectors such as banking, energy, defence and mining, and Kerry stressed that on the US side “we have completed our work, we know what they are, we’re ready.”
The aim was “to use a scalpel rather than a hammer” and to focus on new investment in these sectors, a State Department official said.
“There are plenty of things one can do with a scalpel that create a lot of bleeding, and particularly that have a very strong impact on Russia’s economy, Russia’s future growth, while having minimal impact on us.”
The US official said after the talks that there had been “no dissent” on the need to move to sectoral sanctions if Moscow’s hand is behind any disruption of the vote.
The Russian economy “does have considerable vulnerabilities,” the official said, adding European countries, which have greater economic and energy dependance on Russia than the US, were “becoming increasingly confident that there is a way to do this”.
Ukrainian authorities are also planning to hold new unity talks in eastern Ukraine on Monday, although it had not yet been determined where, the officials said.
Kiev on Wednesday hosted the first round of so-called national unity talks under an OSCE initiative to try to resolve the deepening crisis on Europe’s eastern flank and allow the elections to go ahead.
But crucially, the pro-Moscow rebels fighting against Kiev’s rule in the industrial east of the country were not at the negotiating table, despite Western calls for the talks to be inclusive.
The State Department official said it was understood that on Monday “any political figure, any NGO figure who wants to participate can… the only requirement is that they renounce violence.