Huawei has been at the center of espionage allegations over Chinese 5G network equipment. In 2018, the United States passed a defense funding bill that contained a passage barring the federal government from doing business with Huawei, ZTE, and several Chinese vendors of surveillance products, due to security concerns. The Chinese government has threatened economic retaliation against countries that block Huawei's market access. German and British intelligence agencies have pushed back against the US' allegations, stating that after examining Huawei's 5G hardware and accompanying source code, they have found no evidence of malevolence and that a ban would therefore be unwarranted. Additionally, the head of Britain's National Cyber Security Centre (the information security arm of GCHQ) stated that the US has not managed to provide the UK with any proof of its allegations against Huawei. However, on 14 July 2020 the UK government announced a ban on the use of company's 5G network equipment, citing security concerns. Then in November 2020, Huawei announced that, according to report from business analysts Oxford Economics, it has contributed by £3.3 billion to the GDP, trying to fight back the decision of the UK government. In October 2020, the Defence Select Committee in the UK announced that it found evidence of Huawei's collusion with the Chinese state and that it supported accelerated purging of Huawei equipment from Britain's telecom infrastructure by 2025.