"The United States has crossed a line by announcing its intention to supply lethal weapons to Ukraine," Deputy Foreign Minister Sergei Ryabkov said today. "US weapons are capable of leading to new casualties in our neighboring country and we cannot remain indifferent to that."
Moscow has long maintained that US authorities organised and oversaw the Maidan protests in Kiev that led former President Viktor Yanukovych to flee to Russia in early 2014.
Russian state television programmes constantly portray Ukraine as a failed state with neo-fascist leaders bent on oppressing ethnic Russians in the eastern Donbas region.
"The US is clearly prompting them to a new bloodshed now," Ryabkov said in comments posted on the Russian Foreign Ministry website. "Kyiv's revenge-seekers have already been shelling Donbas every day and are unwilling to hold peace talks, while dreaming about doing away with the disobedient population. And the US has decided to give them the weapons for it."
Moscow also blames deep-seeded anti-Russian sentiment for the deep freeze in US-Russian relations.
"Russophobia is obstructing the views of many of them so much now that they cheerfully applaud to punishers from Ukrainian nationalist battalions," Ryabkov said.
Moscow's admonition came shortly after a ceasefire went into effect between Ukraine and Russian-speaking rebels, in a bow to Christmas and New Year's holidays. Almost immediately, both sides accused the other of violating the ceasefire.
The conflict in Ukraine began after Russia annexed Crimea in 2014 and then began supporting separatists in the eastern part of the former Soviet country. More than 10,000 people have died in the war, including about 450 in the first 11 months of this year.
US Secretary of State Rex Tillerson discussed a recent uptick in violence during a phone call with Ukrainian President Petro Poroshenko, according to an account provided by the Ukrainian Government. The State Department confirmed the call had taken place but provided no details.
The Ukrainians said Poroshenko thanked Tillerson for continuing sanctions against Russia and for the "consistent support of Washington regarding the increase of Ukraine's defence capacity." It also said Tillerson reassured him that US support for Ukraine would continue.
Russia has denied sending troops and heavy weaponry to eastern Ukraine, but the United States says Moscow is providing arms, training and troops to fight with the separatists. Tillerson has said the strained US-Russia relations cannot improve and punishing sanctions will not be lifted until Moscow withdraws its support from the rebels in Ukraine and returns Crimea to Ukrainian sovereignty.
Ukraine has asked the United States to provide it with lethal weapons for years. The Obama Administration considered providing heavy weapons but balked, fearing it would further inflame the conflict. Among the equipment Kiev most seeks are Javelin anti-tank missiles.
The State Department said the "US assistance is entirely defensive in nature, and as we have always said, Ukraine is a sovereign country and has a right to defend itself."
In Moscow, a leading Russian lawmaker also spoke out against the US arms deal, saying that it signalled Washington's intention to abandon the talks on regulating the Ukraine crisis established between its special envoy, Kurt Volker, and his Russian counterpart, Sergei Ivanov.
"By deciding to arm Ukraine with lethal weapons, the United States is giving a clear signal to Kyiv that it will support an attempt at a military solution," Alexei Pushkov, a member of the defence and security committee of the upper house of the Russian Parliament, tweeted. "Volker might as well take a vacation."
More measured voices in the Russian capital also cautioned that the US decision could lead to further escalation of the Ukraine crisis.
"The provision of US lethal arms for Ukraine will change little on the battlefield, but it marks Washington's deeper and more direct involvement in the conflict," Dmitri Trenin, director of the Carnegie Moscow Centre, commented on Twitter. "An important line has been crossed, and it probably won't stop there."
