Updated

Russian President Vladimir Putin on Sunday defended Moscow’s airstrike campaign in Syria while criticizing suspended U.S. efforts to train Syrian rebels to battle ISIS, The Telegraph reports.

Putin claimed Russia’s campaign aimed to "stabilize the legitimate authority" of Syrian President Bashar al-Assad, and said its bombings were already more effective than U.S. efforts. He spoke during a meeting with Saudi Arabia’s Defense Minister Mohammed Bin Salman.

“It would have been better to give us $500 million,” Putin said of the aborted U.S. program to fund the Free Syrian Army during an interview with state-run television, The Telegraph adds. “At least we would have used it more effectively from the point of view of fighting international terrorism.”

Putin added Russia’s involvement was legal because it followed Syria’s request for assistance, and questioned the validity of the U.S.’s program.

“The simplest solution for them would be to join us and, in that way, legalize their actions on Syrian territory,” Putin said of the U.S, The Telegraph reports.

President Obama announced the end of the failed program last week, saying the U.S. will shift its focus to equipping select leaders and providing air support to their units, including Arab and Kurdish groups.

While the U.S. and Russia say they agree on a need to counter ISIS, U.S. officials have criticized Russia’s approach, which comes amid a wave of diplomatic proposals by NATO.

The international organization accused Russia last week of targeting Assad opponents other than ISIS, including some supported by the U.S. and its allies. Activists also claimed Russia targeted historic Syrian sites, such as the ruins at Palmyra, and killed civilians.

Russia has denied the accusations.

Meanwhile, activists said Monday Russian jets have intensified their airstrikes in a central Syrian province. The advance Monday is the latest in a government bid to regain control of areas in the rural parts of Hama, and the Sahl al-Ghab plain. ISIS only has a limited presence on the edges of Hama, away from where the fighting has been concentrated.

The Russian Defense Ministry said it has struck 53 alleged Islamic State targets in the past 24 hours, destroying command centers, ammunition and fuel depots as well as camps where foreign militants are supposedly training.

During the last six days of ground operations, government troops have moved in on two villages in eastern Hama, Atshan and Tal Sukayk, and a third in the plain area. Activists say rebels seized one village south of Idlib.

The Associated Press contributed to this report.