The US just sailed a small aircraft carrier with F-35B stealth jets into the Middle East after Russia threatened US forces.

Russia and its ally Syria are preparing for a large scale assault, which they ominously predicted would involve chemical weapons.

The US said it would strike Syria if the regime used chemical weapons, as the US has down twice before.

Russia sailed a small armada of its navy ships into the Mediterranean and has signaled that it would retaliate against the US if there was a strike.

But with US airpower in the region, now to include stealth F-35Bs, Russia's prospects look limited.

A US aircraft carrier full of F-35B stealth jets showed up in the Middle East after Russia threatened US forces in Syria in the latest military buildup between the world's two greatest nuclear powers.

Russia sailed a small armada to the Mediterranean sea in August as its prepares with its ally, Syria, an offensive against the last rebel stronghold in the country after predicting a chemical weapons attack that it prematurely blamed on US-aligned forces.

President Donald Trump has warned Syria against its offensive against its own people, and the White House said it "and its Allies will respond swiftly and appropriately" to any reports of chemical weapons use in the fighting.

The US has already bombed Syria's government twice over chemical weapons use, both times avoiding Russian retaliation or air defenses.

The US has a small presence of a couple dozen troops advising rebel forces in Southern Syria, which Russia threatened to attack, CNN reported.

The Essex steps up

Wasp-class amphibious assault ship USS Essex (LHD 2) transits the Gulf of Aden during a vertical replenishment while on a regularly scheduled deployment of Essex Amphibious Ready Group (ARG) and 13th Marine Expeditionary Unit (MEU). Photo by Petty Officer 3rd Class Matthew Freeman

Until recently, the US had no capital ships and just one or two destroyers in the Mediterranean, but the USS Essex, a small, flat-deck aircraft carrier used to launch US Marine Corps F-35B stealth jets that can take off almost vertically, just arrived off the horn of Africa, USNI News reports.

Though the Essex remains on the opposite side of the Suez Canal from Russia's ships in the Mediterranean, it's a quick-moving ship. Additionally, the F-35Bs can fly about 550 miles out from the ship in stealth configurations that make them hard to detect for enemy defenses.

Direct combat between Russia and the US remains unlikely, as both sides work together to avoid accidental conflict and neither side seems willing to escalate a fight over Syria into a massive war.

But Syria has hosted the world's liveliest air defense and battle space for years. Missile fires have taken down Israeli, Syrian, and Russian jets over the course of the war. Syria has seen the combat debut of the F-35 and the first US air-to-air kill between manned aircraft since 1999.

The F-35Bs aboard the Essex will train on a variety of missions near the Red Sea, such as how to provide close air support for Marine units optimized to take beaches, or how to respond to an attack.

"Our primary mission is crisis response… being current and absolutely ready for anything the geographic combatant commander needs us to do while we are here," Col. Chandler Nelms, commander of the military expeditionary unit aboard the Essex told USNI.

How the US responds to crisis — even when Russia brings it

An Iraqi T-72 main battle tank destroyed in a Coalition attack during Operation Desert Storm TSGT Joe Coleman

Russia has a larger ground presence in Syria and also operates large groups of mercenaries, but has not fared well in fights against the US so far.

Russia has used military contractors, or unofficial forces, in military operations before as a possible means of concealing the true cost of fighting abroad in places like Ukraine and Syria.

In February, US forces in Syria came under a pro-regime attack made up of hundreds of Iranian, Syrian, and Russian military contractors. A large column advanced towards a US position and began to fire, and the US responded with overwhelming air power and artillery fires that Secretary of State Mike Pompeo would later confirm killed hundreds of Russians.

Allegedly leaked audio recordings from the Russian contractors portrayed a humiliated and cowed force that had gone into a battle seriously outgunned, despite its greater numbers.

Russia has since established a stronger naval position in the Mediterranean with ships capable of firing cruise missiles at targets deep inland, and possibly at the US without risking ground forces.

But, as experts previously told Business Insider, if Russia's navy in the Mediterranean actually killed US forces, the US would swiftly scramble its airpower from across the region and sink the fleet as well as destroying any Russian jets that came to respond.