A terror suspect who apparently plotted to launch an attack in the Netherlands -- and had amassed an AK-47 assault rifle, two full ammunition clips and a painting featuring a flag used by the Islamic State -- was caught by police before he could act, prosecutors announced on Friday.
The news emerged as European Union officials warned ISIS has sent as many as 1,500 terrorists from the Middle East to wage attacks in Europe.
Dutch officials said a search of the man's home as he was taken into custody Wednesday also uncovered four boxes of highly explosive illegal fireworks, phones and $1,687 in cash.
They announced the arrest after the suspect had appeared before an investigating judge in the port city of Rotterdam.
The suspect's identity was not released, in line with Dutch privacy guidelines.
Meanwhile, two teenagers were arrested in Germany on suspicion that they were planning an Islamic extremist attack, prosecutors said.
The two Germans, ages 15 and 17, were arrested on Thursday, according to state prosecutors in Karlsruhe. They said the two were suspected of trying to get their hands on firearms for a possible attack on an unidentified public facility in the Aschaffenburg area, southeast of Frankfurt.
Police seized Islamic extremist propaganda, ISIS flags and phones. They found no firearms.
Prosecutors said Friday there was no evidence the suspects would have been able to carry out their plan, but they were arrested on suspicion of conspiring to commit an attack. Police said they would investigate how serious the plan was and added that there were indications the two were mentally ill.
The Associated Press contributed to this report.