01:56 - Source: CNN
What is Russia up to in Syria?

Story highlights

Russia has said it is delivering weapons to Syria under agreed-upon contracts

U.S. says Syrian President Bashar al-Assad should be out of office, not getting military support

John Kerry has spoken to Sergei Lavrov twice in six days about Syrian civil war

CNN  — 

U.S. Secretary of State John Kerry on Tuesday called his Russian counterpart, Foreign Minister Sergei Lavrov, and discussed the situation in Syria for the second time in the past six days.

The call came as U.S. military officials said they believe Russian troops are trying to set up a military base in the war-ravaged nation.

John Kirby, a spokesman for the State Department, confirmed the call and told reporters Washington is adamant that the government of Syrian President Bashar al-Assad, a close Russian ally, should not get military assistance.

“Nothing’s changed about the fact that – that we don’t want to see the Assad regime getting any support,” he said at a media briefing.

Russia trying to set up base in Syria, U.S. says

Russia said the call focused on Syria and the fight against the Islamic State, or ISIS.

Lavrov stressed again to Kerry the need of creating a united front in fighting terrorists operating in Syria, according to a statement posted on the Foreign Ministry’s website.

Moscow has said it is delivering military equipment to Syria under bilateral contracts, and Russian military advisers are in Syria to instruct al-Assad’s troops how the weapons and systems should operate.

Both Kirby and White House spokesman Josh Earnest said Washington would welcome Russia’s involvement in a coalition fighting ISIS, which controls large portions of Syria.

“What we would rather see (than a military buildup) is the Russians offer up some kind of constructive cooperation with the 60-member anti-ISIL coalition that’s built by the United States and focused on degrading and ultimately destroying ISIL,” Earnest said, using another acronym for the Islamic State.

But Syria cannot be a part of that fight, Kirby said.

“Bashar al-Assad can’t be a member of a coalition that’s fighting ISIL inside Iraq and inside Syria,” Kirby said. “He’s the reason why we are where we are with ISIL.”

Kirby added that the long-term solution to defeating the Islamic State relied on political transition to a new president.

More than 200,000 people have died during the Syrian civil war.

ISIS, a Sunni Muslim terror group, has exploited the chaos and imposed brutal rule on the people in northern and eastern Syria.

CNN’s Jim Acosta and Alla Eshchenko contributed to this report.