|Well, such a thing has been debated quite often, but never with a semirealistc Scenario in mind.
Lets just go with the following quite random timeline:
2005/2006: several minor annoyances and trade disagreements happen between Europe and the USA. Bsuh, who is figures that he needs a populartiy boost seeks a spacegoat and starts a Nation wide Germany and France bashing campaign.
Beeing bashed by Bush promtply leds to the reelection of Chancellor Schroeder.
The European Iranian talks come to a break, Iran stops its Nuclear programm as well as the support of terrorist groups in Israel, in exchange it gains a host of European arms. Amongst them is a shipment of 400 Leopard 2A4 tanks (in fact, Iran gets the Europane equipment the Europeans would have exchanged or upgraded enyway)
In addition, the Iranians grant European companies first rights in developing Iranian Oil fields.
While the irani army is getting trained with their new equipment, a heavy shiite uprising breaks out in eastern Irak. The Shiites demand to be a part of Iran, the rebellion is crushed by the US military.
The US are hit by Terroists.
The Gouverment claims Iran to be the culprit.
The forces that just crushed the Shiite Rebellion in eastern Irak move up the border. Seeing a hole in the Iranian defense, an US general asks for permission to invade and gets it. While diplomatic conuselatins are still ongoing, the US troops overwhelm the tactically suprsied and not fully trained Irani border forces with minimal losses.
The US imprisons the equally suprised European staff still teaching the Iranis.
While US forces are making further progress into Iran, the EU demands the freedom of its instruction staff.
Bush says "that the Europeans can kiss his behind" in an Interview.
German troops surround US bases in Germany.
Seeing America is distracted, Shiite rebels in Irak rise up again.
All European powers cancel any overflight rights to the US that have been previously in place.
A violent Mob lynches several Germans in a rural american willage, the local police stands by, of course this leads to another uproar in the EU.
With aid from local rebels, a British officer of Pakistani origin manages to escape his prison camp. He shoots a GI while doing so.
The American advance is stalled by logistal problems and constant partisan warfare.
Rumors inclince that the runaway British officer is activly particiapting in the Irani resistance.
Pakistan cancel its cooperation with the US.
Under the cover of bad weather, the Iranis start are quick, dedicated and determined counter offensive against the US forces.
The US line is breached. The way of the attack implies the Iranis had satellite info on the American positions, as well as human intelligence sources in the American army.
In addition, the attack was carefully cordinated with partisan activites in the Ameriakn rear.
The American gouverment blames the EU on the defeat and threatens consequences.
Schroeder is cited saying "America and which army?" in a private circle.
A massive American airstrike takes out a lot of Irans ammunition producing facilites.
Several EU cititzens are killed during the attack.
Due to a misprinted order, a imprisoned European instructor is sent to Guantanamo because he shares the name of a terrorist.
The interment of a European instructor interred in Guantanamo is leaked to the BBC.
Diplomatic relations between the EU countries and the USA are severed.
China proclaims its neutrality in an eventual conflict.
Fistfights break out before American Baracks in Germany.
Backed up by reeinforcements, the US manage to flank the Irani force.
Hoping on the fact that the US have other problems to take care off, Iran offers peace talks.
A first ceasefire between Iran and the USA is concluded.
Iran sends some "terrorists" to the US and labels them as the bad evil instigators.
The US refuses to return the still held instructors.
The EU ulitmativly demand the return of the instructors.
German troops move into 2 logistical US bases in Germany and arrest the American troops.
Led by a overly rash American Colonell, a Batallion of bradleys fires at approaching German troops. Beeing led by an equally rash German Oberst, the Leopard 2A6 MBTs fire back.
The USA and Europe are at war.
Now that we have a Scenario, what would be your predictions?