Trump's Iran attack is a huge gamble - and he cannot control the consequences

Donald Trump's decision to launch "major combat operations" in Iran is the biggest gamble by any American president since George Bush invaded Iraq more than two decades ago.

The US commander in chief - who came to power as an arch opponent of the US's so-called "forever wars" - has set out ambitious and extensive goals for his attack against the Islamic Republic, saying he plans to prevent this "wicked, radical dictatorship" from threatening the United States. But he is not in complete control of events.

Mr Trump is gambling that overwhelming US military firepower from the air - rather than boots on the ground - will be enough to destroy the Iranian regime. Tehran's military may have been degraded by previous US and Israeli strikes, but they are showing no sign of rolling over.

Follow live updates here It retains the ability to inflict significant harm against Israel as well as US forces in the region - and is already fighting back. The scale of that retaliation and how much the US and Israel can withstand the counterattacks will be a fundamental indicator to track.

Mr Trump has prepared his country for the potential for American service men and women to be killed, saying in his video address "we may have casualties. That happens in war".

He has calculated that any pain the US side suffers is worthwhile to end the threat posed by Iran. And he spelt out these objectives - a move that could come back to haunt him if they are not achieved.

Chief among these war goals is a vow to prevent Iran from ever having nuclear weapons. But the US president has also pledged to destroy Iran's missile capabilities and to "annihilate" its navy.

He issued an ultimatum to all members of the Iranian armed forces and security services from the Republican Guard to the police, telling them to lay down their weapons "or face certain death". There is no indication that the Iranian security forces are about to betray the regime.

The fact that Iran is now retaliating by launching missiles against Israel is a clear sign that Tehran has not been cowed by Mr Trump's opening salvo and is ready to fight. Even if the regime is toppled, the next moment of peril is what comes next.

The US president made clear that he wants the Iranian people to step up and "take over your government". But, again, he does not have the ability to control what that would look like and whether what comes next is better than what he seeks to destroy.

The history of wars in the Middle East shows that no plan by either side survives first contact with the enemy..