Turkish President Recep Tayyip Erdogan says Turkey had detained one of the Brussels's attackers in June and deported him to Belgium.
For years the EU and Turkey have been working towards tightening security in the wake of terrorist threats coming from the region.
The terror attacks across Brussels on Tuesday throws the spotlight on a new agreement between the EU and Turkey to rein in the flow of refugees crossing European borders.
On Saturday, a suspected ISIL suicide bomber killed four plus himself in one of Istanbul's most popular shopping districts. Intelligence officials later learned they had foiled a attempt to conduct a "Paris style" attack across the city.
This came only days after another terrorist group killed 37 in the heart of the capitol Ankara.
Despite its own domestic problems, Turkey has also been accused of being a transit country for terrorists.
Ankara's "open door" policy for Syrian refugees and its porous landscape leave its borders vulnerable to the illegal crossing of potential extremists.
"They are taking it seriously. A new wall is being built on the Turkish side of the birder with Syrian border and new security and immigration measure are being put in place," said Dr. Ahmet Kasim Han, Political analyst.
"The problem is not stemming out of what is happening right now, the problem is mostly related to what has happened in the past 4.5 years."
Ankara has been criticized for their slow response. Yet, improvements are being seen.
Since the start of 2016, security personnel have captured close to 300 suspected ISIL militants along its border with Syria and over 1200 in the last 14 months, including one of the Brussels's attackers, who was caught in Turkey last June and later deported to the Netherlands.
"One of Brussels attackers was caught in Gaziantep in June 2015, and deported. We reported the deportation to Belgian authorities on July 14, 2015, with a deportation notice," said Turkish President Erdogan said.
"Despite our warning that this person was a foreign terrorist fighter, Belgium authorities couldn`t find a link to terrorism."
Turkey has also taken drastic steps to reduce the threat of potential terrorists leaving the country. Since the agreement to stem the flow of refugee and migrants between Turkey and the EU was signed on Friday, the Turkish coast guard has intercepted more than 2000 migrants, some of which, the EU fears, could have mal intensions.
Yet so far there has been no connection between the Brussels's attackers and the thousands fleeing war and devastation.
One of the suicide bombers in last year's deadly Paris attacks was also deported back to Belgium by Turkish officials for trying to travel to Syria.
