Pakistan may not, at present, be an extremely useful or trustworthy strategic partner for the US. They have been, at times, especially during the Soviet occupation of Afghanistan and the US's subsequent support for anti-Soviet guerillas.
However, as they have amply demonstrated since 2001, their position as a gateway to Afghanistan gives them unique leverage to make life miserable for both Afghans and anyone else involved in that country, which until further developments includes a lot of US troops. It would not be hard to see a "bounty program on US troops via Pakistan". Essentially, what Putin is alleged to have been running and what the US ran on the USSR. Essentially, Kipling's Great Game, 21st century style.
Given Pakistan's economic and political problems they're more a potential spoiler than a really useful ally, but still not a party you want to see cozying up too much to your rivals.
Edit: as a comment rightfully reminds me, I neglected to mention the Taliban
This movement originated from Pakistani madrassas in 94. The level of influence Pakistan still has over them is a good indicator of Pakistani duplicity, even as they pocketed hundred of M$ in US military aid. Or the fact that Bin Laden was able to live unmolested in Abbottabad for years in an area with massive military complexes.
During the Afghan War, some the fiercest battlezones were consistently in the Pech area, which were sitting on infiltration routes from Pakistan into Afghanistan.
Even as Pakistan's ISI sponsored the Taliban, they don't fully control their extremists either, as when a school got attacked. Or when a navy base did.
In short, Pakistan is not the most stable state, there's a tug of war between the government, the military and the extremists. Nor is a very competent one (#120 on 2019 corruption index). The trio of Saudi Arabia, Pakistan and Iran has, very negatively, influenced Islam, just like religious extremists in 16th century Spain did massive disservice to the Catholic religion.
I don't really blame the Pakistani people, they've been duped by their leadership, starting with Zia-ul-Haq who promoted Islam to improve his power base. But you can judge a country by the laws it keeps and few countries sink as low as having the death penalty for blasphemy.
So, less than how useful it can be as a US ally, Pakistan in important in how much of a spoiler it is in the area.