BEIJING: China on Thursday imposed sanctions on 10 US defence firms over arms sales to Taiwan for the second time in less than a week. Subsidiaries of Lockheed Martin, General Dynamics, and Raytheon that had "participated in selling arms to Taiwan" were added to China's "Unreliable Entities List", the country's Ministry of Commerce said. They will be prohibited from import and export activities or making new investments in China, while their senior managers will be banned from entering the country, the ministry said. Last Friday, China announced sanctions on seven US military-industrial companies, including Boeing subsidiary Insitu, also over US military assistance to Taiwan. The self-ruled island is a key point of contention between Beijing and Washington. China claims Taiwan as part of its territory and has said it will not renounce the use of force to bring it under its control. Washington does not recognise the democratic island diplomatically but is its strategic ally and largest supplier of weapons. In December, US President Joe Biden agreed to provide $571.3 million in defence support to Taiwan. The actions "interfere in China's internal affairs, and undermine China's sovereignty and territorial integrity", a Chinese foreign ministry spokesperson said at a regular press conference last Friday. China has intensified pressure on Taiwan in recent years and has staged three rounds of major military drills since President Lai Ching-te came to power in May. On Thursday, China's commerce ministry also added 28 US entities, mostly defence firms, to its Export Control List, banning the export of dual-use items to them. General Dynamics, Lockheed Martin Corporation, and Boeing Defense, Space & Security were among those added "to safeguard national security and interests, and fulfil international obligations such as non-proliferation", the ministry said.