On Wednesday, ISIS forces launched a heavy attack against the Kurdish lines where Canadian special forces are stationed. Maj.-Gen. Charles Lamarre described the attach as "fairly concentrated and well-coordinated," according to the Ottawa Citizen. It was the biggest attack in the region since Western forces arrived 18 months ago.

The three-pronged attack took place along a sector of the Kurdish line northwest of the capital city of Irbil where Canadian special forces have been training the local Peshmerga fighters. The attack spanned five towns in total, including Nawaran, Bashiqa, Tel Aswad, Khazr and Zardik, according to the Vancouver Sun.

The Kurdistan Regional Security Council stated that the attack included "car bombs and mortars and rockets" to open gaps in the line. ISIS fighters followed close behind in an attempt to penetrate any weaknesses.

While there were no reported Canadian deaths, U.S. officials said Islamic State fighters died in the responding air strikes. "This was the hardest punch ISIS had thrown since this summer, and the Peshmerga defeated them," said Col. Steve Warren, a U.S. military spokesman, according to the International Business Times.

Counterattack airstrikes occurred in the following hours. Two Canadian C-18 jets participated in the counterattack air strikes along with U.S., British, and French jets.

While the defense was largely successful, ISIS was able to send fighters through multiple breaches in the line and infiltrate Kurdish communities.

The success of the defense sheds a new perspective on newly sworn-in Canadian Prime Minister Justin Trudeau's pledge to pull Canadian air support based on his election platform.

The question of what "combat" comprises has been the subject of public debate since last winter when it was revealed that Canadian military trainers frequently visit and help to defend the front. During an incident involving friendly fire, Sgt. Andrew Doiron was killed in March, according to the Washington Post.

Canada currently maintains roughly 69 special forces soldiers in the Kurdish area. The soldiers are composed of the Petawawa-based Canadian Special Operations Regiment as well as the Joint Task Force 2 counter-terrorism unit from Ottawa.