Russian warplanes waged heavy attacks against the Islamic State controlled territory in Palmyra, Syria, on Tuesday.

Reuters reports Russian jets hit several ISIS targets in the ancient city, as well as in the neighboring providence of Aleppo in the north.

Syrian state television reported that the strikes targeted and destroyed 20 vehicles and 3 weapon depots in Palmyra. Airstrikes were also waged at the towns of Al-Bab and Deir Hafer in Aleppo, 10 miles east of a military airport overrun by ISIS militants.

According to the Britain-based Syrian Observatory for Human Rights, this was the strongest Russian attack on Syria yet, taking out 15 ISIS fighters and injuring dozens more. The group estimated Russian planes had carried out over 34 airstrikes over the past 24 hours.

Lebanese network Al-Manar television reported that Russia had carried out several raids in the Jabal al-Zawiya area of the northwestern province of Idlib.

Russia's increased military presence in Syria has received mixed responses. The U.S. in particular is critical, as it is believed that Russia's primary objective in Syria is to aid President Bashar al-Assad in his opposition to the country's rebel forces. Last week, the U.S.-led international coalition against ISIS called for Russia to "immediately cease its attacks on the Syrian opposition and civilians and to focus its efforts on fighting Isis."

"These military actions constitute a further escalation and will only fuel more extremism and radicalization," the coalition said in a statement.

However, the Russian attacks have been well received by some in the captured city of Palmyra. The city is a famed archaeological site and has been the target of much destruction from ISIS militants who believe its ancient temples and monuments to be idolatrous and in violation of Islamic law. Last Sunday, the terrorist group destroyed an ancient Roman set of triumphal arches.

Maamoun Abdulkarim, Syrian director of antiques, welcomed the Russian forces in Palmyra.

"If they help us to recover Palmyra, it will be good if it is not too late. We have lost some very important buildings that are very significant for the Syrian heritage," Abdulkarim said to Newsweek.