Visiting Ukraine on Thursday, Secretary of Defense James Mattis hinted that the U.S. government may provide new weapons to Ukraine's military.

Following meetings with Ukrainian officials, Mattis stated, "On the defensive lethal weapons, we are actively reviewing it, I will go back now having seen the current situation and be able to inform the secretary of state and the president in very specific terms what I recommend for the direction ahead." Addressing inevitable Russian criticism, Mattis added, "Defensive weapons are not provocative unless you are an aggressor, and clearly Ukraine is not an aggressor since it is their territory where the fighting is happening."

I believe Mattis will recommend arming Ukraine with Javelin anti-tank missile systems. While President Obama previously rejected that option, it has long been favored by the U.S. military and intelligence community.

Moreover, it's not hard to understand why Ukraine wants these systems.

Since Russia's 2014 invasion of Crimea and southeastern Ukraine, the Ukrainian government has been outgunned in its efforts to wrest back its territory. Javelins offer a way of turning the tables. For the first time, Ukraine's infantry forces could deter, corral and defeat Russian armored forces. This is a special concern in southeastern Ukraine, where Russia has deployed armored vehicles alongside separatist rebels and its own special forces. And because of its design; utilizing two explosive charges — one to breach armor, the other to kill the target — the Javelin system is a major threat to Russian armored forces.

Still, the Javelin does not, as the Russians like to claim, represent a threat to Russian soil. Russia's southern military command (which includes a field army) is located around Rostov-on-Don, just 50 miles from the Ukrainian border. Those assembled Russian forces mean that any Ukrainian invasion would be pointless. The Russians know this, but they pretend they don't know in order to give their opposition to Javelins more moral credibility with the Germans (Chancellor Angela Merkel is wont to appease the Russians wherever possible).

Of course, that doesn't make the choice of supplying anti-tank missile systems an easy one.

It would cause immediate and significant anger in Moscow, so it has to be done on a sufficient scale to make it worthwhile. Unless the U.S. is willing to deploy a significant number of Javelins, Putin won't fear their deployment and will use it as an excuse to for new aggression. Russian strategy in Ukraine remains dynamic; Putin wants to secure a stronger grip over more territory and would use greater force to do so. Deterring that offensive desire would require at least a few hundred Javelins.

Regardless, it seems unlikely that Trump will authorize Javelins to Ukraine. For whatever reason, the president continues to show undue deference to his counterpart in the Kremlin.