By all accounts, the relationship between the United States and Afghanistan looks like that of an unhappy couple forced by circumstances to live under the same roof. This week's happenings more than prove that.

On Monday, the White House had to refute Afghan President Hamid Karzai's scathing remark against the US, saying it was "inconceivable". A day earlier, Karzai had accused the US of colluding with the Taliban because Washington wanted to convince Afghans that foreign forces would be needed to keep peace in Afghanistan even after NATO's current mission ends in 2014.

Karzai's searing remark must have taken visiting US Defense Secretary Chuck Hagel by surprise and marred what otherwise could have been an image-boosting visit for him in the first month of his appointment. This is, however, not the first time that Karzai has lashed out at the US. He once labeled the Americans as "occupiers".