Pakistan has given the US 15 days to evacuate a military airbase, and shut down NATO supply lines to Afghanistan through its territory over the weekend.
It's the fallout of a NATO airstrike on a Pakistani border post near the border with Afghanistan on Saturday which killed at least 24 Pakistani troops. Pakistan says the attacks were unprovoked, while coalition forces say they are investigating the incident.
It has brought the already strained relations between the US and Pakistan to a new low since they became in the war against terror after 9/11.
"Those who are friends of America and NATO are traitors."
That's the rally cry here at this protest demonstration in Karachi organized by the officially banned Jamaat ud Dawa Islamist group.
The turnout isn't huge, just a few hundred people waving black and white Jamaat ud Dawa flag. But it's just one of several such protests across the country on Monday, and follows a larger rally in front of Karachi's US consulate on Sunday.
They are seething against Saturday's NATO airstrike on Pakistani soil. And speakers like Navid Qamar are calling on the Pakistani government to take a stronger response.
"If US or NATO helicopters event enter Pakistan then they should be shot down even if that means following them back into Afghanistan, to take revenge for your martyrs," Qamar said.
The participants at this demonstration are all associated with Pakistan's Islamist parties, and do not represent the bulk of society. But this specific issue of cross-border attacks does resonate across much of the political spectrum in the country.
Many Pakistanis have long been uncomfortable with their government's alliance with the US in its War on Terror.
"Today, NATO forces are spilling the blood of oppressed Muslims in Afghanistan," demonstration speaker Nasrullah Shaji said. "We shared air bases and our intelligence with them. Today those same NATO forces are attacking the Pakistani military."
Many of those at this rally, this is the last straw, and are just as angered by the Pakistani government's weak response as they are by NATO's attacks on Pakistani soil. Abdul Rehman, a spokesperson for the Jamaat ud Dawa, says the killing of uniformed Pakistani troops makes matters even worse.
"If your borders are being breached, your soldiers are being killed then there is no reason to apologize. You just go scramble your jets and raid their posts. That is the basic thing you have to do. Temporarily settlements like asking them to apologize or closing supply lines is not the solution. So there is no point in saying we have our sovereignty. Either give them everything you have, or defend it," Rehman said.
Others, like Asadullah Bhutto of the mainstream Islamist Jamaat-e-Islami party, want the government to take this up with the international community.
"I think it is the right of Pakistan to take this matter to the UN security council and other international forums," Bhutto said. "Because it is a violation of international conventions. They have violated our geographical territory. Govt of Pakistan should take it seriously."
The immediate popular anger in response to this airstrike is likely to eventually die down, as has been the case with previous incidents like this. But what is unclear is what the incremental impact of all of these incidents will be on Pakistani-US relations in the long term.