The news isn't getting any better for Huawei and ZTE. As verbal sabres were being rattled about the arrest of Huawei's CFO in Canada, and her impending extradition to the US to face charges of breaching trade sanctions, the Japanese government slapped a ban on its ministries and defense forces from buying and deploying IT and telecoms equipment from Chinese companies starting in April 2019, citing cybersecurity concerns.

The move, reported by Japan's leading news agency Kyodo, was made following an agreement by Japanese government security officials, and while neither Huawei Technologies Co. Ltd nor ZTE Corp. (Shenzhen: 000063; Hong Kong: 0763) were named in any documentation, the ruling cuts them out of any public procurements.

That ruling is likely to influence the 5G procurement decisions of Japan's three main communications mobile network operators -- NTT DoCoMo Inc. (NYSE: DCM), KDDI Corp. and SoftBank Corp. -- and the upcoming 4G (and 5G) challenger Rakuten that plans to launch services in October 2019, though the latter company has not been including Chinese vendors in its network plans, opting instead to go with Nokia.

The news does not come as a major surprise: Rumors of such a ban on Chinese technology deployments had emerged in August, and even at that time it was anticipated that any ban by the Japanese government would provide strong guidance to the private sector, though none of the operators have issued any public statements saying they will not buy Huawei or ZTE network products. (See Could Japan Also Bar Huawei, ZTE?)

However, it seems highly unlikely that any operator would effectively ostracize itself in Japan, and rule itself out of any government communications services contracts, by deploying Chinese technology. The operator set to be impacted most is SoftBank, which already has Huawei and ZTE technology in its 4G networks and has been testing 5G use cases with the vendors: The Kyodo report cites company sources that say the Chinese technology will be replaced. DoCoMo, meanwhile, has been testing 5G capabilities with Huawei. (See Huawei, NTT DoCoMo Achieve Breakthrough in 5G mmWave Long-Distance Mobility Trial Over 39GHz Band, SoftBank & Huawei Demonstrate 5G Use Cases, Massive MIMO Key to 5G, Says SoftBank and Huawei Launches TDD+ With China Mobile, SoftBank.)

According to this Nikkei Asian review report, citing Tokyo-based research company MCA, Huawei's market share for basestation sales in Japan hit 13% in fiscal 2017, up from 4% in 2016, with SoftBank primarily responsible for that growth.

What are the key technologies and processes that will underpin successful, full 5G deployments? Check out our 5G Big Picture Prime Reading report to find out.

The reaction from the Chinese authorities was swift. During a press briefing Monday, Foreign Ministry Spokesperson Lu Hao responded to a question about Japan's new government procurement rules with the following comment (you can read a full transcript of the press conference here):

The Japanese government decision heaps additional pressure on both Huawei and ZTE, which are quickly finding themselves the pariahs of the international communications networking technology market: They are now effectively blocked from potentially lucrative 5G deals in the US, Australia, New Zealand (at Spark), the UK (at BT) and now, it seems, in Japan. The efforts of the US to paint Chinese technology companies as security threats appear to be having a significant impact.

For more on the increasingly precarious international position of Huawei and ZTE, see:

— Ray Le Maistre, Editor-in-Chief, Light Reading