The US is suffering from a dangerous shortfall in active members and needs 30,000 more on board to combat threats including Russia, China and ISIS, the Air Force chief of staff has warned.

General David Goldfein says that the active duty Air Force needs to grow from 317,000 - its current size - to 350,000. It's currently planned to reach 321,000.

'We just got too small too fast and we've got to grow,' General David Goldfein, the Air Force chief of staff, told USA Today on Wednesday. 'We're at a risk level I'm not comfortable with.'

US Air Force chief of staff General David Goldfein has warned that the US needs to increase its active Air Force member numbers by 30,000 to combat threats around the world

It would take five-to-six years to reach the highest level of militarization recommended by Goldfein, who is currently on a five-day tour of air bases around the country.

But Goldfein, who says his tour has left him concerned about the state of the US Air Force, says that the increase is needed.

It would also require an additional $3 billion a year on top of its existing $151 billion budget.

The US military is increasingly stretched by a troubled - and troubling world.

'It seems like every two weeks we're responding to a crisis or event around the globe,' General Carlton Everhart, commander of the Air Mobility Command at Scott Air Force Base in Illinois, said.

The Air Force is currently engaging ISIS in Syria (F-22 prior to Syrian mission pictured), where Russia is backing the anti-US president but could need to be deployed against China

The Air Force is currently supplying weapons and ammunition to anti-ISIS forces in Iraq and Syria.

But there are forces moving outside the Middle East that could need its attention.

China has increased its presence in the South China Sea, claiming international waters, militarizing artificial islands and flying nuclear bombers around Taiwan.

Tensions between those two countries have been particularly high of late, since President-elect Trump broke US protocol and spoke to Taiwanese President Tsai Ing-wen.

And Russia has increased its presence in the Middle East, backing Syrian President Bashar al-Assad, who opposes both ISIS and the US-friendly Syrian rebels.

Suspected hacks by Russia on the Democratic party during the election also suggest an increasingly militant attitude.