China’s tit-for-tat tariffs on some U.S. imports came into effect on Monday as the trade war between the world’s two largest economies escalates. 

Beijing announced the tariffs last Tuesday, immediately after U.S. President Donald Trump slapped an additional ten percent tariff on all Chinese products.

Starting Monday, China will impose a 15 percent border tax on imports of U.S. coal and liquefied natural gas products and a ten percent tariff on American crude oil, agricultural machinery and large-engine cars.

Last week, Chinese authorities also launched an anti-monopoly investigation into the technology giant Google and imposed export controls on 25 rare metals.

China also added two American firms — biotech company Illumina and fashion retailer PVH Group, the owner of Calvin Klein — to its so-called unreliable entity list.