London (CNN) ISIS' existence is the result of international inaction against the Bahsar al-Assad regime, Turkish Prime Minister Ahmet Davutoğlu told CNN's Christiane Amanpour on Monday.

ISIS "is a product of a crisis, not only a cause of a problem," he said.

His comments come days after his country launched airstrikes against the terrorist group in Syria for the first time, and a week after reaching an agreement allowing America to use Turkish bases for its own missions against ISIS.

The combined effect will be to create a de-facto safe area on a portion of the Syrian border. (A senior U.S. official denied there will be a formal no-fly zone, but admitted to CNN the agreement would have "nearly the same effect.")

"If that was done before, [the] Assad regime wouldn't be killing so many people, or pushing them to Turkey, Jordan, or Iraq or Lebanon. There wouldn't be any place or power vacuum for Daesh, for ISIS, to be active," Davutoğlu said

"Assad lost this legitimacy long before; unfortunately, because of inactivity of international community, he continued his crimes, and he created a power vacuum -- he admitted this vacuum a few days ago -- and ISIS filled this vacuum."

JUST WATCHED Watch the full interview Replay More Videos ... MUST WATCH Watch the full interview 08:44

"Eliminating ISIS is of course a strategic objective, but there should be some other elements," he said. "We have to have a strategy about the future of Syria."

"If there is one person who is responsible for all these terrorist crimes and humanitarian tragedies in Syria, it is Assad's approach, using chemical weapons, barrel bombs against civilians."

Davutoğlu said that while most of the international community agrees al-Assad has no place in the "new Syria," what the "the method" is for achieving that change is an open question.

He called once again for more robust support for "moderate opposition forces" and said "there may not be a need" for international forces to directly battle the regime.

Turkey's strikes against ISIS coincided with a barrage of attacks against the Kurdistan Workers Party, or PKK, in Northern Iraq, with whom the government has waged a long war campaign, and which recently declared a 2013 ceasefire to be over.

JUST WATCHED U.S. strikes from Turkey will have 'really dramatic impact' Replay More Videos ... MUST WATCH U.S. strikes from Turkey will have 'really dramatic impact' 05:06

Brett McGurk, the State Department's deputy special envoy for the coalition against ISIS, told Amanpour the ability to fly missions out of Turkey -- rather than, for example, the Gulf -- "will have a really dramatic impact."

How the United States coordinates with the moderate opposition on the ground is "something that we still have to work out with Turkey."

Davutoğlu denied that his country's strikes in Syria were a "sudden turn."

"We have been very active against any terrorist presence on Syrian soil," he said.

After an attack last week in the Turkish border town of Suruc killed more than 30 people, he said, "it became a necessity to get rid of ISIS from our border."

McGurk said ISIS controls about 90 kilometers of Syria's border with Turkey.

A safe area in Syria would, Davutoğlu said, create a refuge for those fleeing Syria's 4-year-long war and establish a buffer zone with terrorist and "regime attacks."

"To have a safe area for [moderate opposition forces] to control and to receive refugees there will be a strategic asset for the future of Syria and to fight against terror at the same time."

Turkey's strikes against the PKK present a more difficult scenario for the government.

JUST WATCHED Turkish Kurd leader: Strikes about elections, not security Replay More Videos ... MUST WATCH Turkish Kurd leader: Strikes about elections, not security 07:04

Despite the decadeslong insurgency, and accusations that the PKK were behind a recent attack that killed two Turkish police officers, the group's Iraqi and Syrian counterparts have been one of the most effective fighting forces against ISIS.

Davutoğlu said the strikes were only against the PKK -- not the Kurds as a group -- and said "this is a combined fight against terror, against any type of terrorist activity."

Ertuğrul Kürkçü, honorary president of the pro-Kurdish Turkish HDP Party, said the strikes against the PKK were "not an actual security measure against the Turkish guerrillas," but rather "preparing the ground for early elections."

The HDP Party denied the ruling AKP party a majority in elections last month. The country may need to hold a new snap election if the AKP is unable to form a coalition.

"All political actors should be united against terrorism," Davutoğlu said. "Only HDP rejected this request because they had some links with PKK."

"In fact, there is no question about the peace in Turkey. There is a peace in Turkey, and we had a very successful election in June."