Former President George W. Bush deserves "some credit" for the last combat units leaving Iraq on Wednesday night, Sen. John McCainJohn Sidney McCainGOP rushes to cut ties to Moore GOP strategist: 'There needs to be a repudiation' of Roy Moore by Republicans World leaders reach agreement on trade deal without United States: report MORE (R-Ariz.) said.

McCain, one of the foremost supporters of the war effort there, posted a late-night message on his Twitter account, which is followed by 1.7 million people:

Last American combat troops leave Iraq. I think President George W. Bush deserves some credit for victory.

The 2008 GOP presidential nominee's comments suggest that a political debate will likely spring up in response to the troops' exit from the Middle Eastern country.

Reports Wednesday night indicated that the last combat brigade remaining in Iraq departed the country in the middle of the night, beginning the end of combat operations that lasted nearly seven-and-a-half years. 

The war, which began in 2003 under Bush, came to define much of his presidency. Bush drew much criticism for carrying out the long war, which some said was unnecessary and launched on false pretenses.

But Bush received praise in 2007 for launching the troop surge and new counterinsurgency strategy, which helped neutralize insurgent groups operating in the country. 

Later in the day, McCain criticized President Obama's approach to the Iraq War as a senator, saying if he and congressional Democrats had their way, the war would have been lost.

"If Barack ObamaBarack Hussein ObamaOvernight Cybersecurity: What we learned from Carter Page's House Intel testimony | House to mark up foreign intel reform law | FBI can't access Texas shooter's phone | Sessions to testify at hearing amid Russia scrutiny Russian social media is the modern-day Trojan horse Trump records robo-call for Gillespie: He'll help 'make America great again' MORE had his way as a United States senator," U.S. troops would have had to withdraw early and "over time radical Islamic extremists would have taken over that country," the senator said on KFYI Radio in Arizona.

"We would have surrendered — waved the white flag of surrender and lost," he said, adding that "none of those people [Democrats] are being held accountable."

This post was updated at 11:14 a.m.