An international crime ring that imported thousands of kilograms of heroin to the Netherlands was broken up this week with the arrests of three people in Amsterdam and Dordrecht. Authorities said the drugs were brought to the capital to then be distributed back out to Germany, the Scandinavian countries, and the United Kingdom.

Seven others were arrested in Turkey as part of the plot, along with another in Poland and a 32-year-old woman in Belgium, Dutch police said. The three taken into custody in the Netherlands are between the ages of 44 and 50, the latest arrests in an operation spanning over 14 months.

The international police operation included the cooperation of authorities in those countries, as well as Belarus, Germany, Kazakhstan, Italy, Lithuania and Spain. Europol also took part in the investigations.

The Netherlands has been in the spotlight for its work to dismantle large heroin smuggling operations over the past year. A joint investigation between British, Belgian, and Dutch authorities led to the discovery of over 1,300 kilograms of heroin, worth over 130 million euros, a record for Europe. Months earlier, Spanish police arrested 17 people including Dutch-Turkish man Sadullah U., believed to be one of the largest heroin traffickers in Europe.