MOSCOW - Top US diplomat John Kerry is set to meet his Russian counterpart Sergei Lavrov in Rome on Sunday, amid anger in Moscow over the prospect of new US sanctions and possible supply of lethal military aid to Ukraine.
The meeting in Rome will take place with tensions soaring after US lawmakers passed a bill - dubbed the Ukraine Freedom Support Act - which calls for additional sanctions against Russia and the delivery of up to $350 million (S$460 million) worth of US military hardware to Ukraine.
"Undoubtedly, we will not be able to leave this without a response," deputy foreign minister Sergei Ryabkov told Interfax news agency ahead of Lavrov's meeting with Kerry.
The Senate bill must still be approved by the White House, which has so far been reluctant to provide direct military assistance to Ukraine for fear of being drawn into a proxy war with Russia.
The legislation authorizes - but does not legally require - President Barack Obama to provide lethal and non-lethal military aid to Ukraine, including anti-tank weapons, ammunition and troop-operated surveillance drones.
The eight-month-old conflict between government forces and pro-Russian separatists in eastern Ukraine has left at least 4,634 dead and 10,243 wounded, while displacing more than 1.1 million people, according to new figures released by the United Nations.
The threat of fresh sanctions comes as Russia's economy crumbles under previous rounds of Western sanctions and a collapse in oil prices.
Kiev lawmakers have hailed the US bill as a "historic decision". They have long been pressing the West to provide military support to their beleaguered army, but have so far received only non-lethal equipment.
The controversy is likely to come up at Sunday's meeting in Rome, although Ryabkov said that "the main focus at their 17th meeting this year would be on the Middle East".
A State Department official confirmed to AFP that the meeting would be Sunday after Washington had initially said it was set for Monday.
A tentative ceasefire has been in place along the frontline in eastern Ukraine since Tuesday, and fighting has been greatly reduced despite occasional breaches.
The Ukrainian army on Saturday reported 11 attacks on its positions in the past 24 hours but no one was killed or wounded.