President Trump will order "massive" airstrikes against Syrian President Bashar Assad in the event of another chemical weapons attack, a Republican lawmaker predicted.

"We have to maintain that using chemical weapons will cost you far more than any gain you'll get," Illinois Rep. Adam Kinzinger, a member of the Foreign Affairs Committee, told the Washington Examiner. "I think if they're used again, frankly it's gonna be a much more massive campaign."

Trump ordered the first U.S. attack on an Assad regime base in April, following a sarin gas attack against rebels and civilians in northeastern Syria. Fifty-nine U.S. cruise missiles destroyed twenty percent of Assad's air force, according to the White House, although the regime immediately maintained that the base remained functional. That attack outraged Russia, which backs Assad.

"When President Trump acts in Syria, the result is a Russia that complains but can't do much," Kinzinger said.

Russian President Vladimir Putin defended Assad in April by claiming he was a victim of a "provocation," a staged chemical weapons attack intended as a pretext for American intervention in Syria. His team reiterated that position in response to a new warning from Trump that Assad must cease apparent preparations for "another chemical weapons attack" or risk U.S. retaliation.

"We consider unacceptable any such threats to the legitimate government of the Syrian Arab Republic," said Dmitry Peskov, a spokesman for Putin. "We strongly disagree with the wording ‘another attack,' because, as you know, despite all the demands of the Russian side, there was no independent international investigation of the previous tragedy with the use of chemical weapons."

Kinzinger scoffed at that denial. "He sounds like Baghdad Bob a little bit," he said, referring to Saddam Hussein's infamously-optimistic spokesman. "We know that the regime used chemical weapons. No sane person would doubt that. Some crazy people might. And Vladimir Putin and his infrastructure of course might deny that because it would do them no good to admit they were complicit in the least."

Kinzinger added that the United States has "great intelligence capability" in Syria, though he allowed nonetheless that U.S. intelligence officials have to monitor for the possibility that terrorists might try to perpetrate a chemical weapons attack in order to have Assad take the blame. "It's always a danger, anytime you have a nation where it's at civil war with itself and there's chemical weapons that are loose," he said. "But I think it's obvious that up to now it's been in the interest of Assad to [use chemical weapons]."