In 2003 the USA and its coalition partners including the UK invaded #Iraq with the mission 'to disarm Iraq of weapons of mass destruction to end Saddam Hussein's support for terrorism, and to free the Iraqi people.' Without a doubt George Bush got some bad intelligence if this was the justification for the invasion. According to the Washington Post Vladimir Putin government was part of sources of intelligence on Saddam's 'planned' attacks.
Whatever the justification for the invasion was it caused a lot of discontent, in the USA and the UK. Firstly the casualties; a total of 4, 486 US service members was killed between 2003-2012. 179 UK armed forces was also killed during this period. However the number of Iraqi civilian deaths is much higher with approximations going up to 7,500 just for the invasion itself.
This discontent goes some way to explaining why some blame the USA and its partners for recent events in Iraq, but it is not the primary reason.
Saddam Hussein was a Sunni Muslim. Iraq has a Shia Muslim majority. With a large Kurdish population in the north of Iraq. Hussein's Baathist government would not tolerate any sectarian violence within the country so Shia and Kurds were oppressed during Saddam's regime. The removal of Saddam meant that sectarian divisions began to arise. Which is why ISIL or ISIS is a Sunni faction fighting against the Shia controlled Iraqi government.
Therefore then critics argue that if Saddam was still in power he would of controlled the sectarian divisions in Iraq. However there is one issue with this. The situation in Iraq is not a national one, it is a regional crisis with the origins of ISIL being in Syria. Where Assad, who has run a very similar government to Saddam has not been able to control the sectarian divisions which arose after the Arab Spring of 2010.
The Invasion of Iraq in 2003 is not the cause of the crisis in Iraq today. The USA and its partners are possibly still to blame however.
A lack of action in Syria has meant the conflict has gotten progressively worse and has spilled over the Syrian border into Iraq. If there was more political will to challenge Russia, who was the main obstacle to intervention in Syria. Then maybe, the current situation in Iraq may be different.