The two sides will reportedly discuss their energy partnership, which has stalled amid U.S. sanctions against Moscow.
A state-run poll of 1,600 Russians found 89 percent said Russia should not return Crimea to Ukraine in exchange for an end to economic sanctions.
The Ukrainian parliament had earlier approved a law that gave Donetsk and Luhansk a special status of “temporarily occupied."
Worried about a Crimea-like annexation, the Baltic country plans to spend $15.9 million to secure its eastern border.
Residents of the peninsula have seen a marked increase in the cost of living, along with booming property and rent prices.
The foreign minister's comments came as the Ukrainian government was reporting more attacks by pro-Russian rebels.
Putin also said that Russia had saved the life of Ukraine's former pro-Moscow president, Viktor Yanukovich, who he said had been in danger after 'revolutionaries' seized power.
The two leaders spoke by phone Saturday, calling on separatists to respect a ceasefire agreement in eastern Ukraine.
Hungarian and Russian officials deny the lucrative deal is threatened by Euratom's requirements for fuel-supply diversification.
Further economic measures against Russia would be "beneficial to no one," Spain's foreign minister said this week.
Supreme Leader Ayatollah Khamenei is seizing on the letter as political ammunition.
It was unclear whether any potential assistance to the NATO member's eastern neighbor would include U.S.-made weapons.
Several officials disagreed with a SU-25 chief designer who refuted claims that the fighter jet could have downed a passenger plane.
The drills come even as Russia and Ukraine received warnings from several concerned parties to adhere to the ceasefire agreement.
Ketchum pursued a number of controversial campaigns for Russia, including Vladimir Putin's 2013 New York Times op-ed on Syria.
Russia claims that it can host nuclear weapons in annexed Crimea, just as NATO begins exercises in the Black Sea.
Japan is concerned the visit could be taken as a gesture in support of Russian control of the region.
Ukraine says rebels are removing heavy weaponry from the front and concentrating it near Donetsk.
British Foreign Secretary Philip Hammond accused Russian President Vladimir Putin of "subverting" the peace between nations.
The man some call a warlord has praised one of Nemtsov's alleged assassins as a "true Russian patriot."
The IMF's bailout program for Ukraine assumes Kiev will be able to get $15.4 billion from talks with its creditors, according to four sources familiar with the IMF's documents, said an exclusive Reuters report.
The exercises come amid rising concern regarding Russia's actions in eastern Ukraine.