Why the US should help arm Ukraine

The Minsk summit was a last-ditch effort to resolve the Ukraine conflict peacefully. Despite the accord, peace is fragile. Negotiations were held amid escalating violence, as separatists sought to seize more territory before a deal was reached.


Members of the Ukrainian armed forces ride on an armored personnel carrier near Debaltseve, eastern Ukraine, February 10, 2015.
Gleb Garanich | Reuters
Members of the Ukrainian armed forces ride on an armored personnel carrier near Debaltseve, eastern Ukraine, February 10, 2015.

Recall that last September's cease-fire unraveled almost immediately, resulting in the resumption of full-scale deadly conflict.

Read MoreAltman: If Putin reneges on Ukraine, here's what US should do...

This latest cease-fire is a welcome respite to Ukraine's 10-month civil war, which has killed more than 5,000 people and displaced over one million. However, it left critical issues unresolved.

The agreement locks into place territorial gains by separatists in Donetsk and Luhansk, who recently seized more than 500 square miles of territory. Demarcation lines between Ukraine and separatist forces still have to be drawn.

Eastern Ukraine lies in ruin. Its economy is in shambles. Essential services — pensions, health care and education — have been suspended.

Read MoreA turning point in the war against ISIS

Sustainable peace will require constitutional power-sharing giving greater political and economic rights to Ukraine's regions. Failure to addressing these problems could spark renewed conflict.

Russia has meddled in Ukraine's internal affairs, providing heavy weapons and deploying Special Forces. Despite overwhelming evidence, Putin maintains his unbelievable claim: Russia is a bystander to the war.

The United States and international mediators — Germany and France — must be steely-eyed assessing Russia's goals. Here's my assessment of what Putin wants to do:

* Establish a land bridge to Crimea via Mariupol and other Ukrainian lands.

* Undermine Ukraine's efforts to forge closer cooperation with Euro-Atlantic institutions.

* Send a message to Poland and Baltic countries that were part of the Warsaw Pact. There is a price to pay for going against Russia.

Though a cease-fire agreement has been reached, peace implementation will require monitoring, milestones, and enforcement. There is a real risk that Russian-backed forces may launch an offensive in the spring — if not sooner.

Read MoreHow the US and Iran could become BFFs

For sure, there is no military solution to the conflict. Ukraine is no match for Russia's army and well-armed Russian-backed separatists. However, separatists might be more prone towards peace if they felt under pressure from Ukraine's military. Better armed, Ukraine can enforce commitments and make sure the Minsk agreement is implemented.

To this end, the Obama administration is considering providing lethal weapons to help Ukraine defend itself against Russia-backed separatists. Secretary of Defense Ashton Carter addressed the possibility during his confirmation hearing.

The United States should provide security assistance to Ukraine. In addition to a train and equip program, NATO can embed officers in order to upgrade professionalism of Ukraine's military.

Arming Ukraine could deter such adventurism, while sending a signal of solidarity to Ukraine's President Petro Poroshenko, whose government badly needs foreign aid and state-building.

Ukraine has a right to defend itself. It should engage in future negotiations from a position of strength. Arming Ukraine would enhance peace implementation, giving Ukrainians some breathing space to restore the country's war-torn social fabric.

Commentary by David L. Phillips, director of the Program on Peace-building and Human Rights at Columbia University's Institute for the Study of Human Rights. He served as a senior adviser and foreign- affairs experts to the State Department. His new book is "The Kurdish Spring: A New Map for the Middle East."