ISIS may be under pressure in Syria and Iraq, but that may mean greater threats outside the immediate combat zone, which has fueled worries by Western officials. As a result, the United States has compiled a list that it’s circulating to other countries of 19,000 ISIS foreign fighters presumed to be on the loose.

Meanwhile, Interpol also has a list of 173 potential ISIS suicide bombers that may be targeting Europe.

Last week, the head of U.S. Special Operations Command (SOCOM), Gen. Tony Thomas, spoke to the Aspen Security Forum, where he estimated that 60,000-70,000 ISIS fighters had been killed.

US Special Operations Command chief claims '60,000 to 70,000' ISIS fighters have been killed https://t.co/ghQHfAxSD9 pic.twitter.com/0ycY9ul3jB — Business Insider (@businessinsider) July 24, 2017

Ongoing campaigns targeting ISIS in Mosul and Raqqa have made considerable gains, but they have pushed many ISIS fighters out of those areas, with many returning to their home countries. In many cases, these countries don’t even know they’ve returned from the fields of jihad.

In an interview in The New Yorker published on Thursday, Brett McGurk, presidential envoy to the Global Coalition to Defeat ISIS, said that the U.S. has compiled a list of 19,000 ISIS foreign fighters it is circulating to other countries:

When we started, in 2014, ISIS propaganda outnumbered anti-ISIS propaganda six to one [online]. That ratio’s now reversed. Twitter’s taken off hundreds of thousands of pro-ISIS handles. This is a multifaceted effort not just with governments. It is private sector, it is religious, it is civil society. What law-enforcement people need is information. If we get a phone off the battlefield, or a notebook, or an address book, we are able to vet and verify names, and we have now built a database of nineteen thousand names of known foreign fighters who have tried to join or are affiliated with ISIS [or its sympathizers]. We share that with host nations, and they share it with Interpol. TNY: The nineteen thousand fighters, affiliates, and sympathizers—do we believe they are still alive, or are many of them dead? Most of them are alive.

This U.S. list is most likely behind The Guardian report published last week that European countries are on the lookout for 173 potential ISIS suicide bombers that may be intending to target the West.

According to The Guardian:

Interpol has circulated a list of 173 Islamic State fighters it believes could have been trained to mount suicide attacks in Europe in revenge for the group’s military defeats in the Middle East. The global crime fighting agency’s list was drawn up by US intelligence from information captured during the assault on Isis territories in Syria and Iraq. European counter-terror networks are concerned that as the Isis “caliphate” collapses, there is an increasing risk of determined suicide bombers seeking to come to Europe, probably operating alone.

The UK, France, and Germany have already had hundreds of jihadists return from Iraq and Syria:

Earlier this month, I reported here at PJ Media on comments by Sweden’s spy chief, who said they have seen the number of ISIS sympathizers increase tenfold:

Swedish Spy Chief Admits ISIS Sympathizers Have Increased Tenfold to 2,000 https://t.co/8JidsQb3Pp via @pjmedia_com pic.twitter.com/X0Iw6cipyo — Patrick Poole (@pspoole) July 4, 2017

This year we’ve seen a rash of ISIS-inspired terror attacks in Europe, with multiple incidents in Paris and London, as well as attacks in Brussels, Stockholm, and the suicide bombing in Manchester.

2017 Has Seen a Terror Attack Attempted in Europe Every 9 Dayshttps://t.co/pkGilxUGM1 pic.twitter.com/7vyBikhFmf — Simon Harding (@gridnash) May 25, 2017

The scope and scale of the ISIS foreign fighter threat to the West is simply unprecedented. And most of the focus of authorities is on returning ISIS fighters and not on similar threats.

"Up to 65 al-Battar Battalion fighters have returned to the UK from Libya, more than 40 to France and 30 to Belgium" https://t.co/ZzM8NnNdx8 — Max Abrahms (@MaxAbrahms) June 3, 2017

MI5 fears over 60 Somali jihad plotters in UK http://t.co/l8lQoe1u0d — Patrick Poole (@pspoole) September 29, 2013

As I reported here just a month ago, former Western intelligence officials are publicly expressing their concerns that their former colleagues are vastly understating the extent of the potential terror problem.

MI5 figure of 23,000 suspects who pose terrorist threat is probably "the tip of the iceberg" – former intelligence adviser tells #newsnight pic.twitter.com/8rw0LBzf33 — BBC Newsnight (@BBCNewsnight) June 26, 2017

Before the beginning of the Arab Spring and the surge of Next Wave jihadist fighters, terror expert Thomas Hegghammer estimated that in the three decades since 1980, anywhere from 10,000 to 30,000 foreign fighters participated in jihadist wars from Bosnia to the Philippines, which would include the Arab Afghans from the Afghan-Soviet War.

Many of those jihadist foreign fighters ended up as part of the international Al-Qaeda network, conducting attacks over more than 20 years.

Now we’re seeing a new generation of jihadist foreign fighters — with a force nearly the same size — develop in just a few years, not over three decades.

This illustrates that it’s not just a problem in the immediate term. As these fighters return to their home countries — including the U.S. — they will build their own domestic networks that will present an ongoing threat for decades to come.

We’ve already seen the number of terror arrests in the U.S. and the EU climbing (I reported earlier this week on the 130th ISIS-related terror arrest here in the U.S. since March 2014), but the attacks and fatalities are also rising.

Jihadist Arrests in EU Doubled Last Year, Rising for Third Year in a Row: Europol https://t.co/xkOSh7Egqo via @pjmedia_com pic.twitter.com/ylwbhP5Px3 — Patrick Poole (@pspoole) June 16, 2017

#ThanksObama Global Terrorism Has Tripled Since 2011: Now At An All Time High & Up 900% in OECD https://t.co/EVgKJs9SKl via @pjmedia_com pic.twitter.com/0FzJILERd3 — Patrick Poole (@pspoole) June 1, 2017

Terrorism is already at an all-time high, but the spike in terror arrests may not be nearly enough.

What the revelation of the U.S. warning of 19,000 ISIS fighters on the loose around the world may mean is that what we’ve seen is most likely just the beginning.