WASHINGTON (AFP) - The United States has been fighting the Islamic State in Iraq and Syria (ISIS) group in Iraq and Syria since 2014, so has amassed a huge military presence and an array of capabilities in the region.
If President Donald Trump decides to launch strikes against Syrian regime targets in response to Tuesday's suspected chemical attack, the Pentagon has many ways with which to do so.
Any strike against the regime of Syrian President Bashar al-Assad is likely to be conducted remotely to avoid putting US pilots in harm's way.
The US Navy's Sixth Fleet, headquartered in Naples, has two destroyers - the USS Porter and the USS Ross - in the eastern Mediterranean that could shoot a barrage of Tomahawk cruise missiles into Syria.
In September 2014, US ships launched 47 Tomahawk missiles during the first night of strikes against ISIS in Syria.
These missiles can also be launched from attack submarines, but the location of these vessels is secret.
A barrage of Tomahawks could overwhelm any air defences.
Assad's systems are weakened after six years of war but Russia has deployed state-of-the art systems to Syria.
Over in the Persian Gulf, the Navy's Fifth Fleet can quickly respond to military requests in the region.
The USS George H. W. Bush aircraft carrier is also in the Gulf, currently supporting operations against ISIS.
The bulk of US efforts against ISIS in Syria has been conducted from the air, with about 7,500 coalition jet and drone strikes since 2014.
The United States has multiple air bases at its disposal in the region, including Incirlik in south-eastern Turkey, just 100km from the Syrian border.
Among the many air assets available to the United States are its high-tech F-22 Raptors, F-16s and even B-52 heavy bombers.
The F-22, which cost about US$360 million (S$505 million) apiece, is considered the world's most advanced fighter currently operating, thanks to its ability to evade radar.
It can fly faster than Mach 2 and launch laser-guided bombs from miles away.
The Air Force also has at its disposal a fleet of armed Reaper and Predator drones, which use Hellfire missiles to strike targets.
The United States has about 900 troops in Syria - mainly special operations forces - to help train and advise an Arab-Kurdish alliance fighting ISIS.
A Marine artillery unit is helping local forces near Raqa and US forces have expanded a runway at a northern Syria air base to accommodate the huge C-17 military plane, which can bring in armored vehicles and equipment.
The US also has Apache gunships in neighbouring Iraq to support local troops on the ground.