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".

Washington is justified in feeling maligned because the war in Afghanistan has cost it more than 2,000 lives and hundreds of billions of dollars. But despite paying a heavy price for the war, it has failed to convince Kabul that American presence in Afghanistan is a blessing.

This has been a bloody week for Afghanistan, which, along with Karzai's verbal attack, has come as an embarrassment for Hagel. On Monday, a helicopter crashed in southern Afghanistan, killing five American servicemen. Several hours earlier on the same day, two US soldiers and five Afghan army and police personnel were killed by an Afghan policeman in an insider attack in eastern Afghanistan. And deadly weekend attacks killed at least 19 Afghans, including eight children.

Even after 12 years of war, peace and stability remain a luxury for Afghans. A United Nations report released in February shows that 8 percent of the 2,754 Afghan civilians killed in 2012 were victims of Afghan and NATO-led forces. Indeed, US soldiers in Afghanistan have been accused of committing atrocities, including opening fire on Afghan civilians.

Even the US itself is not optimistic about Afghanistan's security prospects either in the short term or in the long run. US National Intelligence Director James Clapper told a Senate hearing on Tuesday: "The Taliban-led insurgency has diminished in some areas of Afghanistan but remains resilient and capable of challenging US and international goals." The assessment is contrary to the Pentagon's usually upbeat evaluation that paints a picture of an impaired and divided Taliban.

The "Global Trends 2030: Alternative Worlds", released by the US Intelligence Council in December, ranks Afghanistan fifth on a list of countries that risk state failure; the country was fourth on the list in 2008. Apparently, the US today lacks the confidence it exhibited a decade ago to help rebuild the country.

If seen in this light, Karzai's remarks deserve sympathy because it is the result of his and his countrymen's disillusionment with Afghanistan's future under the US' shadow.

Increasing rifts between the two sides and their failure to build a truly cordial atmosphere are enough to fuel concerns that US-Afghanistan cooperation this year may not be as smooth as expected, which could jeopardize Afghanistan's security leading up to NATO's withdrawal.

This year, nevertheless, is of pivotal importance for US-Afghanistan ties because the two sides are expected to sign a controversial security pact, launch peace talks with the Taliban and agree on the number of NATO troops to be stationed in Afghanistan after 2014.

The two countries have no option but to cooperate to lay the groundwork for a relatively smooth transition because it will have a significant impact on peace and stability not only in Afghanistan, but also in the entire Central Asian region after 2014.

Apart from mending their ties, Washington and Kabul also have the daunting task of finding ways to strengthen Afghanistan's security network.

Washington needs to take appropriate actions to convince Kabul that it is committed to building peace and stability in Afghanistan even beyond 2014. The US should learn from its lessons in Iraq and ensure that it does not leave behind a big mess in Afghanistan, too. An irresponsible withdrawal would not only let down Afghan people, but also be a blow to the US.

The author is a senior writer with China Daily. E-mail: wanghui@chinadaily.com.cn