A surprise overnight visit to Afghanistan by the new American defense secretary Chuck Hagel turned into a diplomatic headache when a Taliban suicide bomber on a bicycle detonated his explosives outside the Defense Ministry in Kabul. Ten people were killed in the blast and fourteen injured, most of whom were civilians who had congregated near the facility.

A Taliban spokesmen called the suicide operation a message to America’s new defense chief, that despite NATO investment in Afghanistan over the past twelve years, the country remains an incredibly dangerous place and the Taliban still have the strength and freedom to carry out attacks across the nation.

The fact that the blast occurred so close to the visiting secretary — some media reports claimed that Hagel actually heard the explosion when it went off — seems to add some credibility to the Taliban’s message.

Hagel’s trip to Afghanistan came at a particularly stressful time in the broader American-Afghan relationship. In the last two weeks, Afghan president Hamid Karzai has been far more forceful in his speeches and statements, asserting time and again that promoting Afghan sovereignty is a top objective for his government. The issue of Afghan sovereignty has affected just about every major aspect of the NATO’s withdrawal, including control over the detention system and the right to conduct unilateral special forces operations.

A ceremony last weekend that was supposed to mark the official handover of all detainees from American military custody to the Afghan government was canceled over a last-minute disagreement. The site in question is the Parwan Detention Facility north of the capital Kabul which houses thousands of insurgents who have been detained by Afghan and international forces. The detention center is technically under the control of Afghan authorities but American armed forces continue to control several dozen inmates who are considered too dangerous to be released.

Predictably, Karzai wants all Afghan prisoners to be transferred to the Afghan authorities, a demand that American officials are unwilling to fulfill without assurance from the Afghans that these prisoners will be kept in custody.

This is hardly the only dispute between the NATO coalition and the government of Afghanistan.

Last week, Karzai issued a decree ordering all American special operations troops to stop operating in Wardak Province after he received reports from villagers that Afghan commandos under American control were torturing, harassing and killing residents in the area. The United States shot down the allegations after doing an intensive investigation but Karzai is holding firm on his order.

These disputes are a burden to NATO commanders, all of whom are trying to ensure that the environment is as stable as it can be before handing the job of security entirely to the Afghans.

Some of President Karzai’s statements, such as his latest suggestion that the United States and the Taliban were actively collaborating to overthrow his government, have been puzzling, if not downright insulting to American and NATO military officers. But to Karzai and his inner circle, being tough and inflexible during negotiations and at times belligerent against the NATO occupation in public are part of a deliberate strategy to achieve Afghanistan’s full sovereignty after twelve years of foreign involvement. To Karzai, blasting American and NATO involvement as meddling in Afghan affairs is the quickest way to increase his popularity among the Afghan people.

Karzai will be constitutionally barred from running again in the 2014 election so the next year is the last chance he has to assert his own legacy before handing over the reigns of power.