HARI SREENIVASAN, PBS NEWSHOUR WEEKEND ANCHOR: Secretary of State John Kerry made a surprise visit to Afghanistan today in an attempt to ease escalating political tensions there and prolong a power-sharing agreement he brokered two years ago.

Secretary Kerry met with Afghan President Ashraf Ghani, whose security forces control 70 percent of the country's territory but are fighting a resurgent Taliban, which was initially toppled by the U.S.-led invasion in 2001. Kerry also met with Ghani's political rival, Abdullah Abdullah, who is chief executive of the unity government. Kerry later tweeted, quote, "The U.S. continues to support sovereignty, independence and territorial integrity of self- reliant, democratic Afghanistan."

Kerry visited troops serving at Camp Resolute Support in Kabul to thank them for their service. The U.S. plans to withdraw nearly half of the almost 10,000 troops stationed in Afghanistan next year.

Joining me now via Skype from Kabul, Afghanistan, to discuss Secretary Kerry's trip is "Reuters'" State Department correspondent, Arshad Mohammed.

So, first, it seems that there are two sets of problems that Kerry and the Afghans are trying to tackle. On the domestic side, they've got economic problems, political problems, and then they also have the big giant security concerns with the Taliban, which is now heading into its 15th year?

ARSHAD MOHAMMED, REUTERS STATE DEPARTMENT CORRESPONDENT: That's exactly right. On the political side, the problem, essentially, is whether the current national unity government between President Ghani and so-called Chief Executive Abdullah, can continue on beyond what's widely believed here to be the end of its two-year kind of mandate in September. The security problems are well-known. The Taliban has been resurgent over the last year. The fighting season is about to start again. And the U.S. government is planning to cut the number of its troops to 5,500 from 9,800, toward the end of this year.

HARI SREENIVASAN: So what happens on that political front come September? Does that mean the government dissolves or collapses?

ARSHAD MOHAMMED: Well, there's a lot of ambiguity about what exactly happens. What Kerry today said — and he's the person who brokered the agreement that created the unity government — was that from his point of view it doesn't need to end — or it doesn't end in two years, that there's no specific termination date. What he's essentially and what U.S. officials are really trying to do here is to get the Afghan politicians, not just Ghani and Abdullah, but also the opposition politicians associated with former President Karzai to try to work out some kind of an agreement to keep the government going beyond September.

That's especially important because in October, aid donors are going to meet in Belgium and decide how much aid to give to Afghanistan, and they're not going to want to give money if it isn't clear an established government in place to spend the money wisely.

HARI SREENIVASAN: Secretary Kerry had almost a similar trip in Baghdad. There the common foe is ISIS.

ARSHAD MOHAMMED: That's right. We were in Baghdad yesterday, and again, he's trying to push Iraqi politicians to achieve consensus. And the case there, it's really trying to figure out how to craft a cabinet for the Iraqi government that enough of the politicians can live with.

You need to have in general a functioning, somewhat cohesive government, to prosecute the war against the Islamic state militants in Iraq or against the Taliban here in Afghanistan.

HARI SREENIVASAN: Now, when you're on these long plane rides with him and you have access to the secretary, do you ever see his optimism waning? I mean, when you think about this, thousands of American lives have been lost. It's been now 15 years. We've spent probably a couple of trillion dollars in both Iraq and Afghanistan, and here we are in situations where both of these countries, and parts of them, are completely lawless still.

ARSHAD MOHAMMED: You know, my impression is most secretaries of state are almost cogently optimistic because that's part of their job. Their job is to try to find ways to solve problems. We do see Secretary Kerry on the plane off the record sometimes. I can't talk about that. But most secretaries of state I've covered and I've covered for now tend to be looking for solutions rather than wringing their hands over the problems.

HARI SREENIVASAN: All right. Arshad Mohammed joining us today via Skype in the U.S. embassy in Kabul — thanks so much.

ARSHAD MOHAMMED: Thanks for your time.