Editor's note: Teresita C. Schaffer, a nonresident senior fellow at Brookings Institution, is a retired U.S. ambassador to Sri Lanka with long service in South Asia. She is the co-author, with Howard Schaffer, of "How Pakistan Negotiates with the United States: Riding the Roller Coaster." Her analysis appears regularly at South Asia Hand.
(CNN) -- Pakistan and the United States have had a wild ride over the years -- three marriages and two divorces. Events since the start of the year suggest that we may be headed for a third divorce.
The recent announcement that the United States is suspending about one-third of its military assistance is understandable at one level -- but both the United States and Pakistan still need each other, and this is not the way to avoid a breakup.
Since January, the two governments have been trying to renegotiate their "rules of engagement," the basic ground rules for how the two countries, and especially their intelligence services, deal with one another.
Pakistan's policy is driven by the army's anger at the humiliations it has suffered from the United States. As seen from Pakistan, there have been several, but the most important was the raid that killed Osama bin Laden. The team of U.S. SEALs got into Abbottabad, within a mile of the Pakistani equivalent of West Point, picked up and killed its "high-value target," and left without Pakistan's knowing what was up, let alone being asked in advance.
As for the United States, its policy reflects anger at Pakistan's decision to ratchet back the American presence in Pakistan in ways that undercut U.S. strategic objectives. That Pakistan wants to remove Americans charged with implementing the large, agreed-on military support program makes things worse.
Both have good reasons to mistrust one another, including the most compelling reason of all: Their strategic goals have important differences. Pakistan sees its dominant security threat as coming from India; its priority in Afghanistan is to eliminate Indian influence. The U.S. priority is to eliminate al Qaeda from the Afghan scene -- and from the world. As we saw in the Abbottabad raid and Pakistan's reaction to it, when these goals are out of sync, both tend to follow their interests and aren't restrained by the impact on their partners.
But the two countries also need each other. The United States needs access to landlocked Afghanistan, and Pakistan is right next door, by far the easiest access route. It needs at least Pakistani political neutrality to achieve an Afghan political arrangement that it can live with. It needs Pakistan to become politically healthier and to regain some of the economic dynamism it exhibited in the 1950s and '60s to reduce the risk of political and economic turmoil that could spill over beyond its borders.
Pakistan's nuclear arsenal presents a multifaceted security risk the United States will need to address for years to come.
For its part, Pakistan needs the international standing that goes with a strong relationship with the United States; it needs high-end American military equipment; it needs funding on a scale that its other friends (read China) won't be able to supply without the United States; it wants to be able to put some limits, however tenuous, on the expanding U.S.-India relationship.
It's entirely legitimate to signal U.S. displeasure and to rethink military assistance when the conditions for implementing it are not in place. But the aid suspension will not change Pakistan's behavior in ways the United States will find constructive.
The current standoff leaves both sides with the uncomfortable feeling that they must choose between abandoning their strategic objectives and being played for a sucker. Taken to its logical conclusion, it risks open hostility between the United States and Pakistan as they approach critical decisions in Afghanistan. It increases the risk that a small miscalculation by Pakistan or India could heat up that dangerous confrontation.
If there is a way to keep the United States and Pakistan "together" and protect the most important American strategic goals, it starts with reducing U.S. vulnerability. Most importantly, that means a redoubled effort to reduce the amount of material for our troops in Afghanistan that now moves through Pakistan, especially the supplies moving by land.
The next step is to rethink the scale and purpose of the U.S.-Pakistan enterprise. The broad strategic partnership that both countries have talked about for the past decade is currently out of reach. Far better, at this difficult time, to focus on a handful of more concrete and modest goals that both sides can endorse and can publicly acknowledge.
Let's rebuild the relationship around a civilian core. Recognizing the strategic importance of Pakistan's economic development, we have begun to refocus our economic aid on infrastructure that will ease the plight of the cities and encourage job creation. Pakistan's disastrous electricity crisis, with long power cuts, are hitting cities and businesses especially hard, and the U.S. government's decision to reserve part of its economic aid function for expanding power capacity is a step in the right direction
We should accelerate this process. Meanwhile, out of public view, let the military and intelligence institutions of both countries redefine the issues on which the two countries can wholeheartedly work together, and refashion a mutually acceptable security agenda.
This will not eliminate the strategic disconnect that's been the bane of U.S.-Pakistan relations for more than half a century: that's something both sides will have to live with. But it may give us the building blocks from which we can construct some modest successes. If we can do this, that will be time enough to think in more ambitious terms about where our partnership might be going.
The opinions expressed in this commentary are solely those of Teresita C. Schaffer.