A massive military offensive is under way in Afghanistan against the Taliban.

NAWA, Afghanistan (AP) — U.S. Marines suffered their first casualties of a massive new military campaign Thursday as they engaged in sporadic gunbattles along 55 miles of Taliban-controlled heartland in southern Afghanistan.

One Marine was killed and several others were injured or wounded on the first full day of the assault, the largest military operation in Afghanistan since the fall of Taliban government in 2001.

The offensive will test the Obama administration’s new strategy of holding territory and letting the Afghan government sink roots in Helmand province. The insurgency has proven particularly resilient in this area, where foreign troops have never before operated in such large numbers.

President Barack Obama told The Associated Press in an interview Thursday that he has a “very narrow definition of success when it comes to our national security interests” in the region. “And that is that al-Qaida and its affiliates cannot set up safe havens from which to attack Americans.”

And Long War Journal has some disturbing news from eastern Afghanistan: Haqqani Network captures US soldier in Afghanistan.

The Haqqani Network has captured a US soldier who was based in the eastern Afghan province of Paktika. The soldier, who has not been identified, had reportedly been captured after walking off of his small outpost.

The US military has confirmed a solider has been missing since June 30 and believes he has been captured by the Taliban.