(CNN) —  

The US withdrawal of ground forces from Syria most likely means an end to airstrikes, a US defense official told CNN.

US airstrikes in Syria would likely have to stop due to a lack of US spotters on the ground to collect intelligence and call in airstrikes, the official said.

The official also added that it’s possible that drones could still conduct intelligence and reconnaissance missions, just as they do in Yemen and Somalia. Those missions could include strikes, the official said.

Pentagon spokeswoman Cmdr. Rebecca Rebarich told CNN that “as long as there are US troops on the ground we will conduct air and artillery strikes in support of our forces. We will not speculate on future operations.”

Full and rapid withdrawal

In a move that drew criticism, President Donald Trump on Wednesday ordered the “full” and “rapid” withdrawal of US military from Syria, declaring that the US has defeated ISIS.

The US will continue to maintain troops in Iraq, with the capability of launching long range artillery strikes into Syria.

In the days before Trump’s announcement, the US-led coalition in Syria conduced 208 strikes in Syria against ISIS between December 9 and December 15.

While the US conducts many of those coalition strikes, US allies France, the UK and Iraq also carry out air and artillery strikes targeting ISIS.

Coordinated strikes

US Army Col. Jonathan Byrom told reporters earlier this month that Iraqi M-109 Paladins, French CAESAR self-propelled howitzers, and US M777 howitzers were conducting coordinated artillery strikes against ISIS targets in Syria from across the border in Iraq.

A spokesman for the French Defense Ministry told CNN that French military operations against ISIS in Syria would continue.

“It is necessary that the last pockets of this terrorist organization be definitively defeated militarily,” France’s Minister for the Armed Forces Florence Parly tweeted Thursday.

The UK has also been conducting airstrikes in Syria, with British Typhoon and Tornado jets and Reaper drones carrying out dozens of strikes against ISIS targets in recent days, according to the UK Ministry of Defense.

“Much hard work still lies ahead to ensure we win the war,” UK Defense Secretary Gavin Williamson said in statement Thursday.

The US began airstrikes against the terror group inside the country in 2014 under former President Barack Obama.

CNN’s Mike Callahan and Ryan Browne contributed to this report.