By Timothy Heritage and Richard Balmforth
MOSCOW/KIEV (Reuters) - By considering giving weapons to Kiev, the United States could be contemplating a risky venture which advocates say would help end the conflict in Ukraine but opponents warn might fan the flames of war.
A senior U.S. administration official said on Monday no decision had been made on whether to send arms to help Ukrainian forces fight Russia-backed separatists in eastern Ukraine.
Considering such a move stems from frustration with Russian President Vladimir Putin's refusal to blink over Ukraine, despite Western sanctions and a financial crisis in Russia, and concern over a surge in violence in past weeks.
It also reflects a dilemma: what can the West do if sanctions don't work, or don't work quickly?
"A stronger Ukrainian military, with enhanced defensive capabilities, will increase the prospects for negotiation of a peaceful settlement," said a report by the Washington-based Atlantic Council, which suggested military aid should include light anti-armor missiles, drones and armored Humvees.
Such words are welcome to Kiev's pro-Western leaders, whose forces have suffered battlefield setbacks and who accuse Russia of sending troops and weapons to back the rebels.
Right now, Ukrainian troops holding a rail hub near the city of Donetsk are under pressure from separatists, whose artillery and missile attacks are commanded by Russian military specialists.
Russia denies the accusations of direct involvement. It says Washington has shown its true colors by backing what Moscow regards as Kiev's desire to end the crisis by crushing the rebels rather than though diplomacy.
Sending arms to Kiev might not even have much effect on the conflict, critics say, and could encourage a full-scale Russian onslaught on Ukraine's army that might increase the possibility of direct Western intervention.
"Sending weapons is fanning the flame of this conflict and also actually grist to the mill for the Ukrainian government, which is doing everything it can to drag the United States and West further into this dispute," said Otfried Nassauer, head of the Berlin Information Centre for Transatlantic Security.
Western governments have shown little appetite for the idea of sending in international peacekeepers which would likely have to include Russians and would be unacceptable to Kiev.
And a line of thinking may be developing in the West that Putin may only respect force and will only blink if his bluff is called.
By that token, he may change tack if Ukraine is provided with defensive means to turn the conflict into a prolonged struggle which Russia may regret.
On the eve of a visit to Kiev on Thursday by U.S. Secretary of State John Kerry, the stakes are rising, with the rebels and Kiev's forces mobilizing more forces.
A source in the Ukrainian presidential administration said on Tuesday that Ukraine needed as much military help as possible from the West to defend both its border and that of Europe.
Russian officials have rallied round Putin over the annexation of the Crimea peninsula from Ukraine last March and opinion polls show his popularity is high despite the impact of U.S. and European Union sanctions and a looming recession.
Faced by such defiance, the West appears to have few options for increasing pressure on Russia apart from more sanctions, as it has ruled out force.
Providing arms, such as advanced radar systems to counter the rebels' multiple-rocket systems, is still not the preferred option although the U.S. Congress passed the Ukraine Freedom Support Act, providing $350 million in military assistance for Kiev.
"We're not going to bring the Ukrainian military into parity with Russia's military, certainly not in the near future," Ben Rhodes, deputy national security adviser to President Barack Obama, told CNN television in an interview.
"We have to keep the perspective that the best tool that we have to apply pressure on Russia is that economic pressure through the sanctions."
Ukraine's army of 200,000 would be unlikely to match Russian forces if Moscow threw in much larger numbers of troops, possibly backed by air power, to support the separatists.
"Individual supplies of Western arms are not capable of cardinally changing the situation. What is needed is long-term cooperation," said Ukrainian military analyst Serhiy Zgurets.
Practical support is unlikely from the EU and NATO if Washington decides to send in arms. This is important as Washington and the EU are trying to avoid splits which Russia could jump on.
"Until now, the reason we haven't delivered lethal equipment is to avoid an escalation which would involve Russia even more directly," said an official at NATO.
German Chancellor Angela Merkel said on Tuesday her government did not back arming Ukraine with "deadly, lethal weapons" to fight the separatists.
Military commentator Alexander Golts told Russia's Nezavisimaya Gazeta newspaper he did not believe Ukraine could use the weapons it needs without hundreds of U.S. instructors.
"You can imagine the reaction to this by Russia, in the eyes of which it would be NATO being deployed on our borders," he wrote.
(Additional reporting by Juliana Woitaschek in Berlin, Adrian Croft in Brussels, and David Storey and Lesley Wroughton in Washington; Editing by Giles Elgood)