Troop surge
However, only in mid-June 2007, with the full deployment of the 28,000 additional US troops, could major counter-insurgency efforts get fully under way. Operation Phantom Thunder was launched throughout Iraq on June 16, with a number of subordinate operations targeting insurgents in Diyala and Al Anbar Governorates and the southern Baghdad Belts. The additional surge troops also participated in Operation Phantom Strike and Operation Phantom Phoenix, named after the III "Phantom" Corps which was the major US unit in Iraq throughout 2007.

Counterinsurgency strategy: Counterinsurgency strategy in Iraq changed significantly under the command of General Petraeus since the 2007 troop surge began. The newer approach attempted to win the hearts and minds of the Iraqi people through building relationships, preventing civilian casualties and compromising with and even hiring some former enemies. The new strategy was population-centric in that it focused in protecting the population rather than killing insurgents. In implementing this strategy, Petraeus used experience gained while commanding the 101st Airborne Division in Mosul in 2003.  He also explained these ideas extensively in Field Manual 3-24: Counterinsurgency, which he assisted in the writing of while serving as the Commanding General of Fort Leavenworth, Kansas, and the US Army Combined Arms Center (CAC) located there.
Instead of seeing every Iraqi as a potential enemy, COIN strategy focused on building relationships and getting cooperation from the Iraqis against Al Qaeda and minimizing the number of enemies for US forces. The belief was that maintaining a long-term presence of troops in a community improves security and allows for relationships and trust to develop between the locals and the US military. Civilian casualties are minimized by carefully measured use of force.  This means less bombing and overwhelming fire-power, and more soldiers using restraint and even sometimes taking more risk in the process.
Another method of gaining cooperation is by paying locals, including former insurgents, to work as local security forces. Former Sunni insurgents have been hired by the US military to stop cooperating with Al Qaeda and to start fighting against them. To implement this strategy, troops were concentrated in the Baghdad area (at the time, Baghdad accounted for 50% of all the violence in Iraq).  Whereas in the past, Coalition forces isolated themselves from Iraqis by living in large forward operating bases far from population centers, troops during the surge lived among the Iraqis, operating from joint security stations (JSSs) located within Baghdad itself and shared with Iraqi security forces.  Coalition units were permanently assigned to a given area so that they could build long-term relationships with the local Iraqi population and security forces.
However, opponents of the occupation of Iraq, such as retired U.S. Army officer David Hackworth, when asked whether he thought the British military was better at interacting with the Iraqi public than American forces, said "They were very good at lining up local folks to do the job like operating the sewers and turning on the electricity. Far better than us – we are heavy-handed, and in Iraq we don't understand the people and the culture. Thus we did not immediately employ locals in police and military activities to get them to build and stabilize their nation." CNN correspondent Michael Ware, who reported from Iraq since prior to the 2003 invasion, had a similarly dim view of the Coalition occupation, saying that "there will be very much mixed reaction in Iraq" to a long-term U.S. troop presence, adding that "what's the point and will it be worth it?" Ware contended that occupation could "ferment further resentment" towards the U.S.

Results: 

Security situation: For the first few months of the surge, violence increased. However, by the fall of 2007, the security situation had improved significantly.  U.S. military deaths fell from a peak of 126 in May 2007 to 23 in December, and during the period after the surge (June 2008 to June 2011), the monthly average was less than 11.  In May 2007, over 1,700 Iraqi civilians were killed, compared to approximately 500 in December.  The average from June 2008 to June 2011 was approximately 200.

On September 10, 2007, David Petraeus delivered his part of the Report to Congress on the Situation in Iraq. He concluded that "the military objectives of the surge are, in large measure, being met." He cited recent consistent declines in security incidents, which he attributed to recent blows dealt against Al-Qaeda in Iraq during the surge. He added that "we have also disrupted Shia militia extremists, capturing the head and numerous other leaders of the Iranian-supported Special Groups, along with a senior Lebanese Hezbollah operative supporting Iran's activities in Iraq." He argued that Coalition and Iraqi operations had drastically reduced ethno-sectarian violence in the country, though he stated that the gains were not entirely even. He recommended a gradual drawdown of US forces in Iraq with a goal of reaching pre-surge troop levels by July 2008 and stated that further withdraws would be "premature".

While Petraeus credited the surge for the decrease in violence, the decrease also closely corresponded with a cease-fire order given by Iraqi political leader Muqtada al-Sadr on August 29, 2007. Al-Sadr's order, to stand down for six months, was distributed to his loyalists following the deaths of more than 50 Shia Muslim pilgrims during fighting in Karbala the day earlier.
Michael E. O'Hanlon and Jason H. Campbell of the Brookings Institution stated on December 22, 2007, that Iraq's security environment had reached its best levels since early 2004 and credited Petraeus' strategy for the improvement. CNN stated that month that the monthly death rate for US troops in Iraq had hit its second lowest point during the entire course of the war. Military representatives attributed the successful reduction of violence and casualties directly to the troop surge. At the same time, the Iraqi Ministry of Interior reported similar reductions for civilian deaths.

However, on September 6, 2007, a report by an independent military commission headed by General James Jones found that the decrease in violence may have been due to areas being overrun by either Shias or Sunnis. In addition, in August 2007, the International Organization for Migration and the Iraqi Red Crescent Organization indicated that more Iraqis had fled since the troop increase.
On February 16, 2008, Iraqi Defense Minister Abdel Qader Jassim Mohammed told reporters that the surge was "working very well" and that Iraq has a "pressing" need for troops to stay to secure Iraqi borders. He stated that "Results for 2007 prove that – Baghdad is good now".
In June 2008, the US Department of Defense reported that "the security, political and economic trends in Iraq continue to be positive; however, they remain fragile, reversible and uneven."

In the month of July, 2008, US forces lost only 13 soldiers, the lowest number of casualties sustained by US troops in one month since the invasion of Iraq in 2003.  Also, a report by the US embassy in Baghdad, given to Congress in May 2008, and published July 1, stated that the Iraqi government had met 15 of the 18 political benchmarks set out for them.
The Surge allowed troops to have more control over urban areas previously held by insurgents allowing for an overall slowdown of the fighting.

Political system and economy: The US Government Accountability Office (GAO) reported on September 2, 2007, that the Iraqi government had only met three of the eighteen benchmarks created by the US Congress in June 2006. Two other government reports measuring progress in Iraq, a National Intelligence Estimate and an independent commission assessment by retired general James L. Jones, were published for Congress in fall 2007. USA Today compared the findings. The New York Times also did so. Another GAO report stated that the Iraqi Government did not meet 11 of the 18 benchmark measures as of August 30, 2007. On September 14, a White House survey reported "satisfactory" progress on 9 of the 18 benchmarks.
Lionel Beehner Archived 2008-02-21 at the Wayback Machine of the nonpartisan Council of Foreign Relations has called the benchmarks "vague because the metrics to measure them are imprecise." The New York Times stated on May 13 that "Nobody in Washington seems to agree on what progress actually means – or how, precisely, it might be measured." General David Petraeus, commander of the Multinational force in Iraq, has stated that his recommendations on troop strength are not dependent on the Iraqi government's ability to meet the benchmarks.
On December 2, 2007, the Sunni Arab Iraqi Accord Front called for the end to their boycott of the Iraq Parliament. On January 20, 2008, Iraq's parliament passed a law to let members of the Ba'ath party return to public life, a major US congressional benchmark for the success of Iraqi government. That month, the International Monetary Fund (IMF) stated that Iraq's economy would expand significantly from the previous year's lows. Mohsin Khan, the IMF's director for the Middle East, said Iraqi oil production was forecast to climb by 200,000 barrels per day (32,000 m3/d) to 2.2 million barrels per day (350,000 m3/d) in 2008.