The cartoonist most likely refers to the war in afghanistan as ''obama's vietnam'' because

The answer is 'Because President Barack Hussain Obama, decided to continue the War in Afghanistan'

By the end of the 8 years of the Bush era, the Afghan war had dragged on with not a lot of results. It was increasingly becoming unpopular and while Obama had a chance to end the war. It never happened.

More and more Americans and Afghans died with a political stalemate the biggest achievement.

That is why the cartoon describes it as Obama's Vietnam, referring to the now considered, pointless war in Vietnam that cost a lot of lives and money but achieved nothing.

Iwill support us side.