Russia is waging a "holy war" in Syria to protect innocent Christians against the "tyranny of terrorism," the powerful Russian Orthodox Church declared in a statement on Wednesday as Russian warplanes began pounding targets in Syria.

"Russia took a responsible decision to use military forces to protect the Syrian people from the woes brought on by the tyranny of terrorists," Russian Orthodox Church's Patriarch Kirill said in an official statement.

The Patriarch said Russia's armed intervention became necessary since "the political process has not led to any noticeable improvement in the lives of innocent people, and they need military protection."

Archpriest Vsevolod Chaplin, a spokesman for the Russian Orthodox Church, which has 150 million members worldwide, pointed out that President Vladimir Putin's decision to send Russian forces to Syria has the approval of parliament and is "consistent with international law, the mentality of our people and the role that our country has always played in the Middle East," the Interfax news agency said as reported by the International Business Times.

Chaplin said Russia cannot turn its back on Christians and other minority groups being wiped out by Islamic State militants and other extremist forces.

"The fight against terrorism is a holy struggle and today our country is perhaps the most active force in the world to combat terrorism," the Russian Orthodox Church spokesman said.

A senior Muslim cleric has also expressed his support for the Russian military intervention in Syria, saying Syrians are "practically our neighbours."

"We fully back the use of a contingent of Russian armed forces in the battle against international terrorism," said Talgat Tadzhuddin, head of the Central Spiritual Administration of Muslims of Russia, as reported by the RIA Novosti state news agency.

Chaplin said a council representing Russia's other major religions — Orthodox Christianity, Islam, Judaism and Buddhism — will release a joint statement shortly expressing its support for "the decision taken by our government."

Speaking on Russian television, Putin defended his country's military incursion in Syria, Russia's lone ally in the Middle East.

"The only correct way to fight international terrorism.... is to act preemptively, to battle and destroy fighters and terrorists on the territories they have already seized, not to wait for them to come to us," Putin said.

Kremlin Chief of Staff Sergei Ivanov said Russian forces will be targeting ISIS militants in Syria at the request of President Bashar al-Assad.

Earlier on Monday, Putin delivered a speech before the United Nations where he urged the world to support Assad. "We believe it's a huge mistake to refuse to cooperate with the Syrian authorities, with the government forces, those who are bravely fighting terror face-to-face," Putin said.