Europe serves as a "launching pad" for ISIS jihadists to initiate attacks against the United States due to the absence of a cohesive information-sharing strategy among Western nations, former acting CIA director John McLaughlin said Wednesday.

McLaughlin, a 30-year CIA employee who served as acting director under the George W. Bush administration, warned that the absence of effective coordination between European intelligence agencies exposes the United States to greater risk of attack.

Testifying before the House Armed Services Committee, McLaughlin said the Trump administration must work with European allies to establish an intelligence-sharing platform that coordinates Europe's extensive network of security services.

Western Europe has come under heightened pressure to establish such a network as ISIS loses ground in Iraq and Syria, raising the possibility that discouraged terrorists will return home to Europe.

"We have to recognize that as [ISIS is] defeated in Iraq and Syria, if they're not killed and if they don't melt into the population in those areas and retire from a life of extremism, they will go home and they will go home to European services," former CIA director David Petraeus said in congressional testimony.

U.S. defense officials estimate that 1,900 of the roughly 7,000 foreign fighters who left the West to fight for ISIS already have filtered back into Europe. That number is expected to climb due to the U.S.-led offensive to retake Raqqa, the de facto capital of ISIS in northern Syria.

McLaughlin cautioned that the flood of foreign fighters returning to Europe could have a spillover effect in the United States because the region's security services are already "stretched to the limit." The influx is concerning because European passport holders are subjected to less scrutiny than others during entry into the United States.

"If we have terrorists in Europe with passports that don't require the same sort of attention as visas, they can come here," McLaughlin testified.

This challenge has already proved problematic in the Eurozone, where passport-free movement is permitted across most of the 26-member bloc.

Khalid el-Bakraoui, one of the suicide bombers in the March 2016 attacks on Brussels that killed 32 civilians, was wanted by French authorities in connection to the devastating terrorist attacks in Paris four months prior. He was able to enter Belgium after traveling to Greece via Italy.

Both McLaughlin and Petraeus warned against barring travelers from Muslim-majority nations.

Petraeus called on the Trump administration to work as quickly as it can to evaluate what measures the United States can take "to ensure we double and triple check to ensure civilians" entering the country will not cause harm.

The retired four-star general warned that the longer Trump's temporary ban remains in effect, the greater the likelihood Islamic extremists would use it as "ammunition" to recruit jihadists.