Initially ratified in 1987, the Intermediate Nuclear Forces Treaty (INF), which famously kept all nuclear missiles out of Europe for decades, is set to collapse, with US officials saying they will withdraw from the treaty next month.

The US has been accusing Russia of violating the INF for years related to a single missile design, called the 9m729, and its maximum range. The INF forbids all nuclear missiles with ranges between 500 km and 5,500 km.

The core of this issue is that the 9m729 is being designed as a replacement for the 9k720 Iskander, a short-range ballistic missile that has a range of 400 km, and is subsequently compliant with IMF. Russia maintains that the new missile has only been tested to the 400 km range itself, and is therefore also complaint.