For the first time ever, US Air Force F-35As arrived in the UK to train with pilots of the Royal Air Force as tensions between the West and Russia peak.

On the same day that the F-35s arrived in England, two Russian warships passed through the English channel on their way to Syria, in response to the US's April 7 cruise missile strike on a Syrian airfield.

Meanwhile, Montenegro, who the US Senate just backed for ascension into NATO, has an ongoing Interpol manhunt for two Russian operatives they have accused of terrorism for plotting to kill their prime minister. In internal military communications, Russia refers to NATO as the enemy, and they strongly oppose any expansion of the alliance.

As it stands, Russia's forces in eastern Europe far outnumber NATO's so much so that some experts have speculated that Russian forces could seize Baltic capitals within days.

F-35s will have their work cut out for them training against advanced threats like Russia's Su-35. Wikimedia Commons

The F-35s will arrive in Europe at a time when Russian aircraft outnumbers — and in some cases can outperform — legacy US and European aircraft stationed there.

The F-35, with its stealth design and unparalleled information-sharing capabilities, represents a huge step up for US and NATO's air power, as it can improve the performance of legacy planes it flies with by sharing data from its advanced suite of sensors.

Though Russia has long tried to develop counter-stealth technologies and has even taunted the US about its considerable air-defense capabilities, F-35 pilots who spoke to Business Insider said the new fighter would deliver unprecedented capabilities.

The F-35As now at Britain's Lakenheath air base will train with NATO forces to increase interoperability and deter Russian aggression.

Watch the F-35s arrive in the UK below: