The Taliban’s lightning-fast advance into more territory in Afghanistan is causing concern from Russia to China, as US President Joe Biden’s decision to withdraw troops disrupts a power balance in South Asia that has been stable for nearly two decades.

At least 1,000 Afghan troops retreated into Tajikistan this week, prompting the country to mobilize an additional 20,000 soldiers to guard its border. Russian President Vladimir Putin has sought assurances from the Taliban that it will respect the borders of former Soviet Union states in Central Asia, while neighboring Pakistan has stated that it will not accept refugees.

China’s Foreign Minister, Wang Yi, who warned last week that the most pressing task in Afghanistan was “to maintain stability and prevent war and chaos,” plans to visit Central Asia next week for talks about the country. Wang Wenbin, a ministry spokesman, called the US withdrawal “hurried” and said Washington must honor its commitments to “prevent Afghanistan from becoming a haven for terrorism.”

On Thursday, Biden insisted that the US military had achieved its objectives in Afghanistan and would leave by Aug. 31, just shy of the country’s 20th anniversary, despite the deaths of 2,448 US service members and $1 trillion in spending. Nonetheless, the battle for the people of Afghanistan and neighboring countries will continue, threatening, in particular, the $60 billion in projects in the China-Pakistan Economic Corridor (CPEC) right next door.

According to data compiled by the Long War Journal, the Taliban have dramatically expanded their hold on Afghan territory in recent months, leaving the US-backed government in control of just over 20% of the country. The insurgent group now controls 204 of 407 districts, up from 73 at the start of May, while the Afghan government controls only 74. The rest are debatable.

At the moment, Kabul retains control of all 34 provincial capitals, though two are being contested near the borders of China, Pakistan, Tajikistan, and Turkmenistan. In recent weeks, the Afghan Defense Ministry has increased airstrikes against Taliban fighters.

The Taliban’s rapid rise after 20 years of fighting the US risks leading to the collapse of the Afghan government and military, a scenario that occurred in the 1990s after the Soviet Union withdrew. While the United States works to keep al-Qaeda from regaining a foothold in Afghanistan, the consequences for the six countries that border the country are dire– as well as nearby nations like India that have frequently been the target of Jihadist attacks.

The dangers of regional contagion were highlighted in April when a car bomb exploded outside a luxury hotel hosting the Chinese ambassador in the Pakistani city of Quetta, not far from Taliban strongholds in southern Afghanistan. The attack, claimed by the loosely affiliated Tehrik-i-Taliban Pakistan (TTP), demonstrated that governments in the region may find it difficult to protect high-profile diplomats and businesspeople.

Pakistan, which aided the Taliban’s rise to power in the 1990s, is now concerned about a resurgence of the TTP, a group blamed for 70,000 civilian deaths in the country since the United States invaded Afghanistan in 2001. The TTP, which was recently defeated by a combination of Pakistani military operations and US drone strikes, may see an opportunity to attack Chinese projects in order to influence policy in Islamabad.

China, with an economy that has grown roughly five times since the US invasion of Afghanistan, is an especially tempting target. Pakistan’s army has raised a dedicated force of thousands to protect CPEC projects across the country, demonstrating the importance of the relationship between Beijing and Islamabad.

According to Gautam Mukhopadhaya, a former Indian ambassador in Afghanistan, Syria, and Myanmar, a Taliban-led Afghanistan would likely solidify relations between China and Pakistan on one side and the United States and India on the other, with Russia and Iran in the middle to adjust policies depending on threat perception.

As the Taliban gains ground, many Afghans flee to the relative safety of larger cities. Pakistan expects 500,000 Afghan refugees, who will be housed in border camps, according to officials. According to the United Nations High Commissioner for Refugees, more than 1.4 million registered Afghan refugees are already in Pakistan.

According to Madiha Afzal, a non-resident fellow at the Brookings Institution in Washington, a Taliban victory would ultimately embolden all sympathizers across the region.