The United States and Russia have reached a "tacit agreement" on ending the war in Syria, according to a senior adviser to Syrian President Bashar al-Assad. U.S. President Barack Obama and Russian President Vladimir Putin are scheduled to meet on Monday in New York.

"The current U.S. administration wants to find a solution to the crisis in Syria. There is a tacit agreement between the U.S. and Russia to reach this solution," Bouthaina Shaaban, a close adviser to Assad, told Syrian state TV, reports AFP. "The U.S. recognizes now that Russia has profound knowledge of this region and a better assessment of the situation."

In early September, Russia began providing the Syrian army with training, logistical support and heavy weaponry, reported Business Insider. The army is fighting against the Islamic State group as well as against separate U.S.-backed rebel groups who are working to overthrow Assad.

The conflict has killed more than 240,000 people and displaced more than 11 million Syrians since 2011, creating the ongoing refugee crisis in Europe. The U.S. has been funding political opposition groups since 2007, and more recently, providing weapons, training and funds to so-called moderate rebels, according to The Washington Post. The U.S. and its Arab allies have also been conducting airstrikes against the Islamic State group in Syria.

U.S. Secretary of State John Kerry previously said he is willing to personally negotiate with Assad to end the conflict, but suggested that part of the deal must involve Assad stepping down from power. The West has accused him of committing a number of human rights violations.

Russia, however, has refused to accept Assad's departure as a prerequisite for creating peace in the country and said it will continue to prop up the "legitimate government of Syria" and help it defeat the Islamic State group, Sputnik News reports.

"Russia has provided and will provide adequate support to the legitimate government of Syria in the fight against extremists and terrorists of all kinds," Ilya Rogachev, head of Russian Foreign Ministry's Department for New Challenges and Threats, told RIA Novosti on Thursday.

Moscow announced Thursday it plans to hold naval exercises in the eastern Mediterranean Sea in September and October. On Wednesday, the Syrian military for the first time began using Russian drones, and the army has previously received at least five fighter jets along with tanks and artillery.

Now that Russia is militarily involved in Syria, there has been "a change in the West's positions" over the Syrian war and the crisis "is heading towards detente and towards a solution," according to Assad's adviser.

As Stratfor writes, "Russia has rightfully judged that its direct intervention in Syria will force Washington to begin direct military-to-military talks with Moscow on the conflict."

The White House announced Thursday that Obama and Putin will meet Monday afternoon in New York during a three-day session of the U.N. General Assembly, reported The New York Times. The two will discuss the conflicts in both Syria and Ukraine.