When leaders from 90 nations sit down today to discuss the future of Afghanistan in Bonn, Germany, Pakistan's seat will probably be empty. Amid a climate of worsening relations between Washington and Islamabad, that absence should be worrying leaders on both sides.
Officially, the boycott is over Nato's raid last month that killed 24 soldiers on Pakistan's soil. But there is a more fundamental issue: Pakistan is preoccupied, some would say to the point of paranoia, with its regional position, particularly when it comes to its fratricidal relationship with India.
Washington has to understand that it is forcing Islamabad's generals into a corner. With US approval, India has been exerting a greater presence in Afghan affairs, both in terms of investment and security. News this week that as many as 30,000 Afghan soldiers will be trained on Indian soil during the next three years will only feed fears in Pakistan.
Outmatched on the battlefield, hopelessly uncompetitive in economic terms, Pakistan relies on friendly relations with Afghanistan to prevent encirclement. Islamabad has long sought a pliable government in Kabul, at times with Washington's complicity.
During the mid-1990s, Afghanistan's Taliban government denied India political and military influence, and helped Pakistan maintain Pashtun cohesiveness in the tribal areas. Support for select militant groups - the Haqqani Network and Lashkar-i-Taiba among them - might be unsavoury, but for Pakistan it has served as insurance.
There is no easy resolution to this tangle of interests. US forces backed by Nato are unlikely to stop targeting militants, including self-professed Al Qaeda terrorists, on Pakistani soil. And every strike inflames Pakistani public opinion, weakens the few remaining US allies in Islamabad and makes it harder for Pakistan's generals to work with their US peers.
Pakistan shares too much with Afghanistan over the porous Durand Line for one country to become stable while the other is not. The United States, and India for that matter, might be able to get the upper hand in the Afghan government, but long-term regional stability depends on Islamabad as much as Kabul.
There will be other empty chairs in Bonn today. There are no Taliban representatives on the list of attendees. Nor is it clear whether diplomats from neighbouring Iran or Uzbekistan will be present. But it is the empty chair reserved for Pakistan that will loom over the proceedings.