A British woman who worked at the top of the US military during the most troubled periods of the Iraq war has said she fears the west has yet to see how some Muslims brought up in the last decade will seek revenge for the "war on terror".

Speaking for the first time about her experiences, Emma Sky also questioned why no officials on either side of the Atlantic have been held to account for the failures in planning before the invasion.

Sky, 44, was political adviser to America's most senior general in Iraq, and was part of the team that implemented the counterinsurgency strategy that helped to control the civil war that erupted in the country. The appointment of an English woman at the heart of the US military was a bold and unprecedented move, and it gave her unique access and insights into the conduct of one of the most controversial campaigns in modern history.

In all, the Oxford graduate spent more than four years in Iraq, including a spell as civilian governor of one of its most complex regions. She met Tony Blair and Barack Obama in Baghdad and earned the trust of senior Iraqi officials, as well as many of the country's leading politicians and community leaders, some of whom remain her friends.

Now back in London, Sky has been reflecting on her time in Iraq in a series of interviews with the Guardian. She expressed concern about the effects this period has had on the Arab world, and how some of the mistakes made in Iraq appear to have been repeated in Afghanistan.

But Sky also defended the military and the senior commanders she worked with, who, she said, did everything they could to retrieve the situation.

She argued politicians and government officials on both sides of the Atlantic should have been held responsible for the decision to go to war, and the lack of strategy and planning for its aftermath – the consequences of which are still being felt.

A lack of understanding of the Arab world also meant the west struggled to grasp why it had provoked so much violence, and who was responsible for it.

"We've been fighting the war on terror for 10 years" said Sky. "At times it seems we have been fighting demons. We behaved as if there were a finite number of people in the world who had to be killed or captured. And we were slow to realise that our actions were creating more enemies.

"It has been seen by many Muslims as a war on Islam. Now, we are saying, 'We've pulled out of Iraq, we are pulling out of Afghanistan, and it's all over now.' It may be over for the politicians. But it is not over for the Muslim world. Well over 100,000 Muslims have been killed since 9/11 following our interventions in Iraq and Afghanistan, mostly by other Muslims.

"We have to ask ourselves, what do we think this has done to their world? And how will they avenge these deaths in years to come? It is not over for the soldiers who have physical injuries and mental scars, nor the families who have lost loved ones."

She added: "The world is better off without Saddam. But nobody has been held accountable for what happened in Iraq, and there is a danger that we won't learn the right lessons, particularly related to the limitations of our power.

"Politicians can still claim that Iraq was a violent society, or that Iraqis went into civil war because of ancient hatreds, or the violence was the inevitable result of the removal of Saddam, or that al-Qaida and Iran caused the problems. They distract from our own responsibility for causing some of the problems by our presence and the policies we pursued."

She said the focus on building up local security forces in Iraq and Afghanistan was not the right priority.

"We think it is about us, and it is about our security. But in the end, it is about their politics … success in Iraq was always going to be defined by politics. We needed a political solution, a pact, a peace."

Sky was one of the British volunteers who went to Iraq in the aftermath of the invasion to help the reconstruction effort being led by the Coalition Provisional Authority.

She was appointed civilian governor of Kirkuk, the oil-rich city in the north of the country, and impressed US commanders with the way she worked with an American brigade to bring stability to the region.

Her frankness about the problems facing the country, and the coalition's difficulties in dealing with them, did not deter the American military from recruiting her in 2007. She was made political adviser to General Ray Odierno, the US commander sent to Iraq to oversee the military "surge" – which involved 20,000 extra troops being sent to the country to stem the violence.

In 2008, Odierno succeeded General David Petraeus as overall commander of forces in Iraq. He asked Sky to return with him in the same advisory role. Odierno is now chief of staff of the US army and Petraeus is director of the CIA.

As a civilian member of Odierno's team, Sky accompanied him everywhere, and was given responsibilities that seem remarkable for a "foreigner". She witnessed some of the horrific violence that led to tens of thousands of Iraqis, and thousands of coalition troops, being killed. A number of people she considered friends – Iraqi and American – died in the fighting.

An Arabist who spent 10 years working in Jerusalem, Sky said: "I had worked in places overseas for a long time, but I had not worked with people who were then killed – sometimes due to their association with me. That first year in Kirkuk, I spent a lot of time with the provincial council and about a quarter of the people on the council were killed.

"There was always that sense that we had come into their lives and said, 'Who is going to stand up and serve their province?' and they had come forward, and some of them had been killed. If we had never come into their lives that might never have happened."