The Obama administration is planning direct talks between Russian and American military officials soon over Russia's military buildup in Syria, a development that has flummoxed the U.S.

Secretary of State John Kerry told reporters in London that President Barack Obama believes military-to-military discussions with Russia are "an important next step" as the U.S. and its allies seek to resolve a worsening Syria crisis while also trying to understand Russia's burgeoning role. Russian Foreign Minister Sergey Lavrov first broached the idea earlier this week in a phone call with Kerry.

The Pentagon will take the lead in the discussions, but Kerry shed no light on the exact level, venue and timing except to say, "I think, hopefully, it will take place very shortly." The Pentagon has not yet weighed in on what its role will be in the talks.

"This (Syria) crisis has got to be solved," Kerry said before meeting with the United Arab Emirates Foreign Minister Abdullah bin Zayed.

Most military talks with Russia were suspended after Russia annexed the Crimea region of Ukraine.

Dismissing American concerns, Russia has stepped up its military support in recent weeks of Syrian President Bashar Assad, who the U.S. believes must leave power.

U.S. officials said in recent days that they are seeking answers to myriad questions about the precise reasoning behind Moscow's recent deliveries of material and manpower to a base in northern Syria.

After their third phone call on the Syria situation since Labor Day weekend, Kerry said Wednesday that Lavrov had proposed a "military-to-military conversation and meeting in order to discuss the issue of precisely what will be done to de-conflict with respect to any potential risks that might be run and have a complete and clear understanding as to the road ahead and what the intentions are."

"You have to have a conversation in order to do that," Kerry said previously. "It is vital to avoid misunderstandings, miscalculations (and) not to put ourselves in a predicament where we are supposing something and the supposition is wrong."

Kerry said Lavrov had told him that Russia was only interested in confronting the threat posed by the Islamic State group in Syria. But Kerry stressed that it remained unclear if that position would change and Russia would mount a defense of Assad.

"Obviously, there are questions about that," he said. "I am not taking that at face value."

However, Kerry added that if Russia's attention is on the Islamic State group, then it remains a potential partner in pushing for a political transition in Syria. "If Russia is only focused on ISIL and if there is a capacity for cooperation ... there still is a way to get a political negotiation and outcome," Kerry said, using an alternate acronym for the Islamic State.

Russia's military buildup in Syria has perplexed the Obama administration and left it struggling to respond. In the wake of U.S.-Russian cooperation over the Iran nuclear deal, U.S. officials had hoped Russia would also cooperate on Syria. But Moscow's latest actions have alarmed many observers, who see them as a naked grab for Middle East influence.

In recent days, Russia has sent about a half-dozen battle tanks and other weaponry — along with military advisers, technicians, security guards and portable housing units — to Syria with the apparent goal of setting up an air base near the coastal town of Latakia, a stronghold of the Syrian president.

A U.S. intelligence official said Russia's moves in Syria reflect growing alarm about Assad's ability to weather opposition gains and suggests that Moscow may be willing to intervene directly on his behalf. Russia's military involvement raises a number of concerns, especially because it does not appear to be coordinated with the other countries operating in the area, said the official, who was not authorized to speak publicly about the subject and spoke on condition of anonymity.