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CARL AZUZ, CNN 10 ANCHOR: First topic today on CNN 10. We're breaking down American and Russian tensions over what's happening in the Middle Eastern country of Syria.

I'm Carl Azuz. It's good to have you watching.

U.S. Secretary of State Rex Tillerson arrived in the Russian capital yesterday. He's meeting with his Russian counterpart, Foreign Minister Sergey Lavrov.

The main subject: Syria's ongoing civil war. Last week, dozens of Syrians were killed by a chemical weapon, a poisonous gas. The U.S. blames Syria's government for launching the attack and though Syria denied it, American ships later fired missiles at a Syrian air base, the base where the U.S. says the chemical attack was made from.

This was the first time that America targeted a Syrian government position. Previously, it had only gone after ISIS terrorist positions in Syria.

But here's where it gets more complicated — Russia supports the Syrian government and its president, Bashar al-Assad. And the U.S. does not.

So, America is trying to influence Russia to end its support for Syria's leader.

REX TILLERSON, UNITED STATES SECRETARY OF STATE: We want to create a future for Syria that is stable and secure. And so, Russia can be a part of that future and play an important role. Or Russia can maintain its alliance with this group which we believe is not going to serve Russia's interest longer term.

FREDERIK PLEITGEN, CNN SENIOR INTERNATIONAL CORRESPONDENT: Faced with new Russian threats, the U.S. military not backing down in the skies over Iraq and Syria. We're on a KC-10 tanker plane refueling the fighters pounding ISIS.

Of course, there's some tension since the Russians have announced they don't want to communicate with the U.S. anymore in the skies over Syria. That's why crews like this one take great care when they fly into Syrian air space.

Stopping the communications significantly increases the risk of mid-air collisions over this crowded air space where U.S. coalition and Russian planes operate very close to one another.

Russia made the move after America hit a Syrian airfield with cruise missiles last week in response to a chemical attack on a Syrian village killing around 90 people.

Washington blames the Assad regime, Russia's main ally in the civil war there, even as Syria denies being behind the attack.

But America doesn't want the turmoil to affect the ongoing effort to destroy ISIS.

Despite the current tensions with Russia, the U.S. says that the fight against ISIS has to continue full steam, especially with American and allied forces on the ground and in harm's way.

A sentiment echoed by commanders leading the air war against ISIS.

BRIG. GEN. CHARLES CORCORAN, U.S. AIR FORCE: We can't take our eye off the ball. It is — it is ISIS. That's why we're here.

So, you know, our national leadership decided to do something about a problem that they saw and — and if we're asked to help out with something like that, we're obviously ready to do it. But, right now, ISIS is the game.

PLEITGEN: So far, the U.S. says there have been no incidents involving Russian planes over Iraq and Syria and they hope, despite Russia's rhetoric, that it stays that way.

Fred Pleitgen, CNN, aboard a KC-10 refueling jet over Iraq and Syria.