Russian President Vladimir Putin and U.S. President Barack Obama meet for the cameras before the start of a bilateral meeting at the United Nations headquarters, Sept. 28, 2015, in New York City. Chip Somodevilla/Getty Images

UPDATE: 8:40 p.m. EDT--The meeting between U.S. President Barack Obama and Russian President Vladimir Putin Monday evening on the sidelines of the U.N. General Assembly was, "businesslike back and forth," according to a senior administration official, a White House correspondent reported. The first half of the 90-minute meeting was spent discussing Ukraine while the second half was spent discussing Syria, the official said. The two world leaders disagreed on the role Syrian President Bashar Assad will have in resolving the civil conflict there.

The U.S. does not view Russia's military build-up in Syria as necessarily destructive to a positive outcome in Syria, but the administration's view on the Russians is dependent on their actions going forward.

Overall, the official described the meeting as productive. “This was not a situation where either one of them was seeking to score points in a meeting. I think there was a shared desire to figure out a way in which we can address the situation in Syria," the official said, according to a White House correspondent.

UPDATE: 7:40 EDT -- After U.S. President Barack Obama and Russian President Vladimir Putin met for their first formal meeting in over two years, Putin said he doesn't rule out joining air attacks against the Islamic State group in Syria, but will not send ground troops into combat, the Associated Press reported. Putin said the talks were "very constructive, businesslike and frank." The two leaders talked about the U.S.-led coalition's action against ISIS, Putin said, the AP reported. He did not mention Russia's actions in backing rebels against Ukraine or its takeover in Crimea.

Original Story:

U.S. President Barack Obama and Russian President Vladimir Putin met for the first time in over two years for a one-on-one meeting Monday evening on the sidelines of the U.N. General Assembly, the Associated Press reported. While the U.S. administration reportedly wanted to focus on the Ukraine crisis and the status of a peace plan, Russian officials sought to emphasize Syria.

A senior U.S. official told Reuters that Putin had requested the meeting. "Given the situations in Ukraine and Syria, despite our profound differences with Moscow, the president believes that it would be irresponsible not to test whether we can make progress through high-level engagement with the Russians,” the official said, Reuters reported.

White House officials have complained about Russia’s recent military buildup in Syria, and the two countries’ opposing positions were apparent Monday when Obama and Putin clashed in contrasting speeches over the fate of Syrian President Bashar Assad. In his address, Obama reprimanded Russia for its defense of the Syrian government, its takeover of Crimea and its activities supporting Ukrainian rebels, the New York Times reported. The U.S. has said that Assad's removal from the presidency is essential to stabilizing Syria, while Iran and Russia have said that his regime is necessary in order to fight terrorism.

“In accordance with this logic, we should support tyrants like Bashar al-Assad, who drops barrel bombs to massacre innocent civilians, because the alternative is surely worse,” Obama said in remarks aimed at Putin, the Guardian reported.

U.S. President Barack Obama and Russian President Valdimir Putin toast during a luncheon hosted by U.N. Secretary-General Ban Ki-moon during the 70th annual U.N. General Assembly at its headquarters in New York City, Sept. 28, 2015. Getty Images

Putin, on the other hand, did not back off on his position of supporting Assad. He asserted that the Syrian president represents stability, and in order to fight Islamic State group extremists, his forces need support.

“We think it’s an enormous mistake to refuse to cooperate with the Syrian government and its armed forces, who are valiantly fighting terrorism face to face,” Putin said, the New York Times reported.

Relations between Russia and the U.S. over the past year have been strained. Due to Russia's actions in the conflict in Eastern Ukraine, the U.S. imposed sanctions on Russian officials and companies. However, Russia has denied any direct military involvement in the conflict, which began in 2014, and has accused the U.S. and NATO of infringing on its rightful sphere of influence in Eastern Europe.

The last time Obama and Putin met was during the G20 summit in Australia last November, according to CNN. During the 70th anniversary of D-Day in June, the two leaders briefly talked regarding the crisis in Ukraine. Monday was the first time in nearly a decade that Putin showed up to talk at the UN General Assembly.