President Barack Obama and Russian president Vladimir Putin were scheduled to speak before the United Nations Monday, setting out plans to address a four-year Syrian civil war that has left the country devastated.

Obama was among the first to speak at the General Debate of the 70th United Nations General Assembly, which began this Monday. Obama took the opportunity to heavily criticize Russia in its approach to the situation in Syria.

"On this basis, we see some major powers assert themselves in ways that contravene international law," Obama said. "We're told that such retrenchment is required to beat back disorder, that it's the only way to stamp out terrorism. In accordance with this logic, we should support tyrants like Bashar al-Assad."

Obama also called out nations such as China and Iran for their roles in a number of international conflicts.

Obama's speech came just before Putin address to the U.N. Afterwards, Obama and Putin will meet together to help resolve tensions and come to a possible compromise regarding the Syrian crisis.

The U.S. is concerned about Russia's military intentions in Syria. Recently, news broke of Russia sending increased numbers of military vehicles and equipment to a Russian air base in the war-torn country. It is believed Russia intends to support Syrian President Bashar Assad in his fight against the rebel groups that helped spark the current war.

The U.S. has taken a different approach, helping to support the rebels in ousting Assad. The White House has accused Assad of using inhumane tactics, such as aerial strikes and shelling that have resulted in mass civilian casualties. The war has also led to a refugee crisis in Europe.

The U.S. has argued that ending Assad's regime is the best path to bringing peace and unity back to Syria.

"We can't just keep donating to take care of refugees. We have to prevent the refugees from having to be refugees, from having to leave their homes," said Secretary of State John Kerry to USA Today. "The world is looking at this and wondering whether the institutions that have been created for so long to deal with these kinds of issues are going to come together and function."

Putin has criticized the U.S. for its support of the Syrian rebels. On Sunday the Kremlin released video on an interview with CBS and PBS, in which the Russian president mocked efforts to equip and train the rebel forces.