Turkey on Tuesday appealed for more help in cracking down on foreign fighters flooding to join terrorists in Iraq and Syria, revealing it had placed 12,800 people on a no-entry list, AFP reports.

Turkish Foreign Minister Mevlut Cavusoglu met with his American counterpart John Kerry in Washington to discuss wide-ranging efforts to combat a slew of upheavals in the Middle East, saying it was a “critical time for our region.”

Turkey’s shared borders with Syria, Iraq and Iran have made it a vital crossroads in efforts to combat the threat of Islamic State (ISIS) terrorists as well as to search for a solution to end the four-year Syrian war.

The United States and Turkey in March began training and equipping thousands of moderate Syrian rebel forces as part of a deal signed after several months of negotiations.

But Turkey’s hesitation to take robust action against ISIS in the U.S.-led coalition had led to strains in its ties with the United States.

Ankara, which is also hosting some two million Syrian refugees, was an “essential partner” in the efforts to combat the Islamic State group, Kerry said ahead of their talks at the US State Department.

ISIS forces “are under increasing strain, its leadership has been degraded, its finances have been squeezed and its hateful ideology has been discredited,” he added, according to AFP.

At the same time, Kerry warned that as ISIS had weakened, it had “become more dependent on new recruits.”

Many recruits have come from Gulf nations, but there has been alarm at the increasing numbers joining ISIS from Europe.

That meant countries had to redouble efforts to “persuade and prevent young people from making the fatal mistake of signing and then travelling to and trying to cross the border into Syria,” said Kerry, according to AFP.

Cavusoglu revealed that Turkey had placed more than 12,800 people on a list barring them entry to the country amid fears they could try to slip into either Iraq or Syria.

A further 1,300 foreign fighters had been deported, he said.

“Turkey is one of the transit countries for foreign fighters, and we have been doing our best to stop them,” Cavusoglu said.

“But the source countries should also do their best to support and to stop foreign fighters before they leave,” he argued.

“We need better cooperation, we need timely information sharing and also intelligence.”

Turkey has in the last few months been repeatedly criticized by its Western allies for not doing enough to halt the flow across Turkish territory of European nationals seeking to join ISIS jihadists in Syria.

However, it has made a number of arrests in recent months and insists it is doing all it can to control the border.

Several weeks ago, a British woman was detained by Turkish police on suspicion of seeking to join Islamic State terrorists in Syria, and was later deported back to Britain.

Previously, three British teenager boys suspected of trying to travel to Syria were detained by Turkey and later deported to Britain.

Ankara was sharply criticized over its failure to stop three British teenage girls who crossed the Turkey-Syria border to join ISIS in February.

The three teens, Shamima Begum, 15, Amira Abase, also 15, and Kadiza Sultana, 16, are now feared to have reached the conflict zone and are believed to be staying at a house in the city of Raqqa, a stronghold of ISIS.