A Ukrainian serviceman talks on his mobile phone as he stands in a military truck outside Debaltseve, eastern Ukraine February 10, 2015. (REUTERS/Alexei Chernyshev)

In Washington, there are growing bipartisan calls to arm Ukraine as it combats a resilient Russian-backed insurgency in the country's east. The pro-Moscow separatists stepped up their offensives into government-held territory, adding impetus to the efforts of European diplomats who hoped to convene peace talks between Ukraine and Russia in the Belarusan capital Minsk on Wednesday.

But some in the United States are wary of more failed negotiations. President Obama admitted that his administration is considering sending "lethal defensive weapons" to the government in Kiev. And the usual suspects in Congress are adamant this is the best path to curbing Moscow's new revanchism, which they say is responsible for a conflict that has claimed more than 5,000 lives already.

The most cited argument calling for arms transfers was articulated in a report authored by a roll call of Washington foreign policy luminaries and jointly published last week by the Brookings Institution, the Atlantic Council and the Chicago Council on Global Affairs, which is headed by Ivo Daalder, a former U.S. envoy to NATO. It's titled, "Preserving Ukraine's Independence, Resisting Russian Aggression: What the United States and NATO Must Do."

It claims Moscow's current intervention in Ukraine is "the gravest security threat to the transatlantic community and Eurasia since the end of the Cold War" and "an unacceptable challenge to the post-war European security order." Russia has "grossly violated" previous commitments to respect Ukraine's sovereignty and territorial integrity, not least by annexing Crimea last March. Now, the report concludes, "the West needs to bolster deterrence in Ukraine by raising the risks and costs to Russia of any renewed major offensive."

That means one main thing: "providing direct military assistance" to Kiev, a wide array of materiel and weaponry that include antitank missiles, armored Humvees and surveillance drones. The goal is to help Ukraine "inflict significant costs" on the separatists and their alleged Russian backers so that it makes an already embattled Russian President Vladimir Putin rethink his strategy as casualties, including among Russian soldiers, mount.

Here are some reasons to doubt the success of such a plan.

Don't underestimate Russia's commitment to the fight.

Neither the authors of the report nor any other serious advocates of arming Kiev believe that better arming Kiev will actually enable Ukraine's government to defeat the Russian-backed forces. As Jeremy Shapiro, a Brookings scholar who recently wrote what serves as a dissent to his boss's report, points out, the calculus is both cynical and perhaps naive, given Moscow's willingness to provoke bloodshed in the region.

"It is hard to find comfort in a plan whose success relies on Vladimir Putin's sensitivity to death," Shapiro writes, noting the surging anti-American sentiment in Russia. Direct U.S. military aid to Ukraine would only deepen the anti-West, "anti-imperialist" narratives that have dominated airwaves in Russia over the past year and would reinforce the Kremlin's own messaging about the conflict as an existential struggle for Moscow's future.

"This coercive strategy is also unlikely to work, no matter how much punishment the West inflicts," writes the international relations theorist John Mearsheimer. "What advocates of arming Ukraine fail to understand is that Russian leaders believe their country’s core strategic interests are at stake in Ukraine; they are unlikely to give ground, even if it means absorbing huge costs."

There's another line of argument that stresses that, for Putin, the power play in Ukraine is all that he may have left. Harvard's Stephen Walt, a known skeptic of U.S. interventionism, spells out what's at stake for Russia:

Russia is not an ambitious rising power like Nazi Germany or contemporary China; it is an aging, depopulating, and declining great power trying to cling to whatever international influence it still possesses and preserve a modest sphere of influence near its borders, so that stronger states — and especially the United States — cannot take advantage of its growing vulnerabilities.

Ultimately, as Walt notes, "Ukraine's fate is much more important to Moscow" than it is to those who happen to be animated by it right now in Washington. In this standoff, it's hard to believe Putin would ever be the one to blink first.

The U.S. has been here before.

Here's how Zbigniew Brzezinski, former secretary of state in the Carter administration, described the American reaction to the Soviet invasion of Afghanistan in 1979.

We immediately launched a twofold process when we heard that the Soviets had entered Afghanistan. The first involved direct reactions and sanctions focused on the Soviet Union.... And the second course of action led to my going to Pakistan a month or so after the Soviet invasion of Afghanistan, for the purpose of coordinating with the Pakistanis a joint response, the purpose of which would be to make the Soviets bleed for as much and as long as is possible.

The legacy of that American plan to build up the Mujahideen and "make the Soviets bleed" is, of course, still being unraveled. No one wants an Afghanistan scenario, but the calculation behind arming Kiev now is not that different from the one in Brzezinski's mind more than three decades ago. Sanctions are already in play; some members of Congress think it's time to apply even more pressure.

American interventions almost invariably seem to turn into thorny entanglements with unforeseen complications and consequences.

Even the very tentative and limited plans to better equip Ukraine's troops present a series of tricky questions: Who will train an army mostly equipped with Soviet-era gear to use American weaponry and technology? Would that require U.S. personnel on the ground? Wouldn't that provoke Russia further? And would it not then raise the stakes of the crisis as well as the specter of a proxy war that many Americans would not want?

The only solution is a diplomatic one.

There's a reason that European leaders, including those of Germany, France and Britain, are desperately seeking a cease-fire rather than an escalation of the conflict. Ultimately, the only imaginable solution is a diplomatic settlement that turns down the heat in the region and allows for rapprochement between Russia and its western neighbors. An influx of Western weaponry and military aid could have the opposite effect, paralyzing any hopes of a diplomatic breakthrough and perhaps even prompt a full-scale Russian invasion.

The harder question is what happens to Ukraine: its military is outgunned; its economy is in tatters; and whole tracts of Ukrainian land are now out of its government's control. The Kremlin has made clear it has no interest in letting it slip from Moscow's orbit.

Those against arming Ukraine, such as Mearsheimer and Walt, believe the only viable outcome is a Ukraine that is "a neutral buffer state in perpetuity" between the West and Russia. Tufts University professor Dan Drezner, writing on Post Everything, pours a bit of cold water on that, given the obvious European aspirations of many Ukrainians and the polarization that has set in over the past year. The best choice could be to settle for a "festering, frozen conflict." But that may be preferable to an explosive, expanding one.