Are Tony Blair and George Bush 'war criminals'?

[OSR stands with Israel]

anyone starting a war of agression is a war criminal.

A "war of aggression" against a tyrant is not a crime, neither is one against a planned ethnic  cleansing, like the Kosovo bombings.

War crimes should be reserved for warfare using massacres, execution of prisoners, mass rape, forced enlistment of civilians, child soldiers or other actual crimes. It is pointless to call any attack on any country a crime. Individual US soldiers and "security contractors" did some crimes in Iraq, but that weren't part of the overall political or military strategy to an extent where you can say Bush was a war criminal, and this is even more true for Blair (there were fewer British violations of the Geneva convention).

A crime is a legal concept, and there are international laws regulating warfare. Just calling everything you morally disagree with "a crime" is pointless. Use another word for that.

Lets just take a Wiki excerpt to get a rough idea of what we are talking about:

"A war crime is a serious violation of the laws and customs of war (also known as international humanitarian law) giving rise to individual criminal responsibility. Examples of war crimes include:

- murdering, mistreating, or deporting civilian residents of an occupied territory to slave labor camps
- murdering or mistreating prisoners of war or civilian internees
forcing protected persons to serve in the forces of a hostile power
- killing hostages
- killing or punishing spies or other persons convicted of war crimes without a fair trial
- wantonly destroying cities, towns, villages, or other objects not warranted by military necessity"

(there are of course other types of war crimes, but this covers the most important ones apart from mass rape)

The US did the bolded and you can argue they did the last to some extent (but also argue against it with good reasons), but it wasn't on the Presidents order. There isn't any serious basis for holding Dubya personally responsible for war crimes during the iraq War, and even less for Blair.