Obama and Putin to hold tense meeting over Syria crisis

President Obama will address the United Nations General Assembly in New York Monday.

He'd hoped to use his trip to the U.N. as a victory lap for the diplomatic breakthroughs with Iran and Cuba. Instead, they'll be overshadowed by the crisis in Syria, which is forcing him to hold a rather tense meeting Monday with Russian President Vladimir Putin, reports CBS News correspondent Margaret Brennan. The meeting comes amid Russia's growing presence in the war-torn country.

It is the first time the two world leaders are meeting in more than a year. Putin's recent military buildup in western Syria -- seen in satellite images -- blindsided U.S. officials, who fear more bloodshed.

Mr. Obama's isolation of Putin after the Russian seizure of Crimea failed to stop him from further meddling in Ukraine, and with the U.S. reluctant to act in Syria, Putin has stepped into the void, taking advantage of the chaos to prop up his longtime ally, Syrian President Bashar al-Assad. Putin also claims he'll begin to fight the Islamic State of Iraq and Syria, better known as ISIS.

"The risk of having Russia involved in Syria is that suddenly it becomes not just a regional problem of a Syrian civil war but a great power conflagration," Andrew Tabler of the Washington Institute for Near East Policy said.

The White House was also caught off-guard Sunday when the Iraqi government announced it would share intelligence on ISIS with Russia, Syria and Iran.

"I think we have concerns about how we're going to go forward," Secretary of State John Kerry said.

In a meeting with his Russian counterpart, Kerry said the U.S. needs to know what Putin is planning.

French warplanes carried out their first airstrikes in Syria on Sunday.

U.S. intelligence officials estimate that the number of foreign fighters joining ISIS in Iraq and Syria has doubled in the past 12 months to 28,000 volunteers from over 100 countries.

And a $500 million U.S. program to train and equip Syrian rebels has largely failed. Fewer than 100 are on the battlefield, and some recently gave their weapons to the al Qaeda-linked Nusra Front in exchange for protection.