Eight other people were wounded in the attacks in the town of Tal Afar, they added.
"The strategy that worked so well in Tal Afar did not emerge overnight, " the president said.
One of the Iraqi soldiers who fought in TAL Afar was a private named Tarek Hazem.
McMaster, commander of the Army's 3rd Armored Cavalry, which is responsible for security in Tal Afar, told CNN.
Tal Afar is located about 150km (90 miles) east of the Syrian border and 420km north-west of Baghdad.
"The example of Tal Afar gives me confidence in our strategy, " he said.
McMaster said he believes recent arrests in Tal Afar and at the Syrian border have significantly disrupted the insurgency's ability to operate.
Soldiers have been moving earth to construct a trench and a berm around Tal Afar, forcing traffic to go through rather than around security checkpoints.
The progress of the Iraqi forces is especially clear when the recent anti-terrorist operations in Tal Afar are compared with last year's assault in Fallujah.
The head of Iraq's intelligence academy and two bodyguards have been killed in a suicide blast in the northern town of Tal Afar, police say.
One Task Force Lightning soldier died and another soldier was injured in the incident, which occurred in Nineveh province, where Mosul and Tal Afar are located.
The mistake was that, you know, we left Tal Afar to its own devices, and it's not surprising that they had the opportunity to get back in there.
But there's a lot of positive foundation in Tal Afar in my view and it would not take much to get that thing back on the right course again.
But look, Tal Afar was an area that we had secured - we have secured the population and we changed the level of violence rather dramatically, we enfranchised the local leadership.
Just a year ago, Tal Afar, the city up near the Syrian border in the northwestern part of the country, was cited as an example of this is how we should do it.
Many of the people outside the administration who have been most prominent in proposing this have been people like General Jack Keane, a recently retired general, and a lot of people who are active in Tal Afar, which is a place where the clear hold-and-build strategy actually worked.
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