WASHINGTON - The Pentagon said on Monday that the US military will continue to support Afghan troops as Taliban militants seized several cities over the weekend.

The security situation in Afghanistan is "clearly not going in the right direction", Pentagon Press Secretary John Kirby told reporters in a briefing.

"We will continue to support them with the authorities we have, where and when feasible, understanding that it's not always going to be feasible," he said. "But where and when feasible, we will continue to support them with airstrikes, for instance."

He noted that the Afghan forces have the capability and advantages in combat with the Taliban, stressing the need for Kabul to exert both political and military leadership.

Kirby declined to speculate if the US military will continue to provide air support for Afghan forces beyond Aug 31, the date that President Joe Biden had ordered the US military to end its mission in Afghanistan.

The US military conducted airstrikes against Taliban militants in recent days as the insurgent group made rapid advances in the battleground and claimed to have captured six provincial capitals after heavy clashes.

Many Afghan cities and about half of the country's 34 provinces have seen heavy battles and street fighting in recent weeks as Taliban militants continued fighting against security forces.

Given the deteriorating security situation, the US Embassy in Kabul on Saturday urged all Americans to leave the country immediately via available commercial flights.