The escalation of violence in Syria can be directly tracked to the United States' unwillingness to get involved in the country, Sen. John McCain asserted.

"Because of our failure to assist, because of our failure to lead other willing nations in the region like Turkey and Saudi Arabia and Qatar and others, the situation has now deteriorated to a situation which is really, really very dangerous," McCain said on CNN's "State of the Union."

The Arizona Republican's comments came as fierce clashes erupted on Sunday between forces loyal to Syrian President Bashar al-Assad and rebels in Aleppo, Syria's most populated city.

Opposition activists said an entire building collapsed in the city after being targeted by a tank belonging to al-Assad's regime. The latest violence comes after 16 months of bloodshed that began in March 2011, when a fierce government crackdown against protesters morphed into a nationwide uprising against the regime.

McCain, the highest-ranking Republican on the Senate Armed Services Committee, said Sunday that the situation in Syria could be remedied but that it would be unnecessarily difficult given the lack of action by President Barack Obama's administration.

"It is retrievable, but it is far, far more difficult and complicated than if we had weighed in a long time ago," he told CNN Chief Political Correspondent Candy Crowley.

McCain said Obama and his administration have "relied on the goodwill of Russia" in their dealings with Syria, calling that approach "shameful."

"We keep pushing the reset button that Russia and China -- and now we are bound by the decisions of the U.N. Security Council which are dictated by Russia and China," he said. "We need to get arms and equipment to them and establish a buffer zone."