US soldiers rush for cover through an opium poppy field in Kandahar province [Getty]

US legislators opposed to the Afghan war have pushed to pull US forces out of Pakistan in a blunt challenge to President Barack Obama.

As the US Army opened a criminal investigation into a huge leak of military files to the whistleblowing website Wikileaks, Obama said the documents showed he was right to craft a new Afghan war-fighting approach and vowed to stick with it.

“We have to see that strategy through,” said the president on Tuesday, who declared the roughly 92,000 newly revealed documents “don’t reveal any issues that haven’t already informed our public debate on Afghanistan.”

His comments came as the House of Representatives geared up for votes on an emergency spending bill to pay for his plan to turn around the faltering campaign and on a measure calling for a withdrawal from Pakistan.

“Wake Up America. WikiLeaks‘ release of secret war documents gave us 92,000 reasons to end the wars. Pick one,” Democratic Representative Dennis Kucinich, author of the Pakistan measure, said as debate began.

Debate on funding