Russia on Monday blamed the Israeli Air Force for the deadly airstrike on a Bashar al-Assad air base after a suspected chemical attack killed at least 60 in a Damascus suburb over the weekend.

Russia's Defense Ministry said two Israeli fighter jets launched the attack on the T4 air base in central Syria from Lebanon's air space.

Syria shot down five out of the eight missiles that targeted the base, the ministry said. It said the other three landed in the western part of the T4 base.

The airstrikes reportedly killed 14 people, including Iranians, at a military airport near the city of Homs.

A Syrian military official also said Israel was behind the attack.

Israel has struck inside Syria in recent years. No country has taken credit for the airstrike.

Saturday's chemical attack unfolded in a rebel-held town near Damascus amid a resumed offensive by Syrian government forces after the collapse of a truce.

Syrian activists, rescuers and medics said a poison gas attack in Douma killed at least 60 people, with families found suffocated in their houses and shelters. The reports could not immediately be independently verified, , but a Syria medical relief group on Monday said over 1,000 were injured in the attack.

The Union of Medical Care Organizations, a coalition of international aid agencies that funds hospitals in Syria and which is partly based in Paris. said the death toll is likely to rise.

“The numbers keep rising as relief workers struggle to gain access to the subterranean areas where gas has entered and hundreds of families had sought refuge,” the group said in a statement.

Images released by the Syrian Civil Defense White Helmets, a volunteer organization, showed children lying on the ground motionless and foaming at the mouth. The Assad government denied responsibility.

The Pentagon denied any involvement in the airstrike overnight at the Syrian air base.

“However, we continue to closely watch the situation and support the ongoing diplomatic efforts to hold those who use chemical weapons, in Syria and otherwise, accountable,” a Defense Department spokesman said.

On Sunday morning, Trump condemned the latest attack as "mindless," referred to Assad as an "animal" and said Russian President Vladimir Putin was "responsible" for enabling the carnage.

The president also warned Russia and Iran that there would be a "big price to pay" for backing the Assad regime and slammed former President Barack Obama, who vowed in 2012 that such actions would cross a “red line,” but later failed to enforce the promise a year later when hundreds of Syrians were killed by sarin gas. Instead, Obama brokered a multi-nation deal in which Assad pledged to remove his chemical-weapons stockpile.

Trump was to meet with his senior military leadership on Monday, the same day his new national security adviser, John Bolton, assumes his post. Bolton has previously advocated significant airstrikes against Syria.

Fox News' Lucas Tomlinson, John Roberts, Travis Fedschun, Edmund DeMarche and the AP contributed to this report.