BEIJING (Reuters) - Chinese and Kyrgyzstan border forces held exercises on Tuesday in China’s Xinjiang region to bolster defenses against the smuggling of weapons, China’s state media reported.

China has stepped up security in Xinjiang in its far west amid fears of attacks by militants from the mostly Muslim Uighur ethnic minority. A car bomber attacked the Chinese embassy in the Kyrgyz capital of Bishkek last year.

Helicopters, armored jeeps and 700 border police officers from the neighbors took part in the exercise in Xinjiang’s Kirgiz Prefecture, China’s official Xinhua news agency reported.

The drills were observed by officials from all countries in the Shanghai Cooperation Organization, a security bloc jointly led by China and Russia, that includes Kazakhstan, Kyrgyzstan, Russia, Tajikistan, Uzbekistan, India and Pakistan, it said.

Chinese officer Chen Dingwu, who was in charge of he exercise, told Xinhua the troops were simulating weapons smuggling by militants from Kyrgyzstan into China.

Video footage broadcast by China’s state media showed a police van cutting off a mini-bus and then speedily reversing away through simulated explosions as an attacker struck the van’s windshield with a baton.

Other footage showed helicopters firing what appeared to be live missiles at a mountaintop target, jeeps mounted with machineguns subjected to simulated ambushes, and officers practicing riot control with police dogs.

Beijing says security in Xinjiang is under threat from militant separatists, in particular from the East Turkestan Islamic Movement, which China says stirs up tension between members of the Uighur community and ethnic majority Han people.

Rights groups say that much of the unrest and violence in the region is a result of Chinese government policies that restrict the cultural and religious freedoms of Uighurs. China denies treating anyone unfairly.

Kyrgyzstan’s state security said the August 2016 attack on China’s embassy, in which the car-bomber and was killed and three people were wounded, was ordered by Uighur militants in Syria and carried out by a member of ETIM.

Xinjiang is an important section of China’s Belt and Road initiative, President Xi Jinping’s plan to expand trade and energy networks along the old Silk Road to the Middle East and Europe beyond.

Xinjiang shares a 5,700 km (3,540 mile) border with eight separate countries and has 15 dry ports.