The UK is probing NVIDIA’s purchase of Arm Holding, citing concerns over national security.

NVIDIA announced last September it had entered an agreement to purchase Arm. Arm’s chip designs are used by companies around the world, including Apple, Qualcomm, Samsung and more. Almost immediately, critics decried the deal as an effort by NVIDIA to reduce competition, with concerns the company would save Arm’s best work for itself. In contrast, Arm has built its business by being strictly neutral, licensing its designs to anyone that wanted them.

There have also been major concerns regarding the UK semiconductor industry, with Arm being the most successful example. Given the increasing nationalization of the semiconductor industry, many critics worried about the UK losing its most prominent chipmaker to acquisition by a US firm.

It appears the UK government shares those concerns, and has filed an “intervention notice” to investigate the deal based on national security concerns, according to Reuters.

“As a next step and to help me gather the relevant information, the UK’s independent competition authority will now prepare a report on the implications of the transaction, which will help inform any further decisions,” said digital minister Oliver Dowden.

NVIDIA has downplayed the issues, saying its deal does not pose a threat.

“We will continue to work closely with the British authorities, as we have done since the announcement of this deal,” said NVIDIA.