US Secretary of State Mike Pompeo on Thursday demanded an immediate reduction in violence in Afghanistan for the peace process to go forward after what he said was an "unacceptable" spike in Taliban attacks.

"The upsurge in violence in parts of Afghanistan over the last couple days is unacceptable," he said at a news conference. "Violence must be reduced immediately for the peace process to move forward."

US and Taliban negotiators signed an agreement on Saturday laying out a path toward peace that could lead to the withdrawal of US and foreign forces within 14 months. The signing in Doha was preceded by a week-long reduction in violence across the country.

But on Wednesday, the Afghan interior ministry said the Taliban had carried out 30 attacks over a 24-hour period that resulted in the deaths of four civilians and 11 Afghan soldiers.

General Mark Milley, the chairman of the Joint Chiefs of Staff, downplayed the severity of the attacks in congressional testimony Wednesday. "What is important, though, for the agreement: we're on day four, this was small, low-level attacks, out on checkpoints, etcetera," he told the Senate Armed Services Committee.

Denounces 'reckless' ICC decision

Pompeo also attacked as "reckless" a ruling by international war crimes judges that a probe into wartime abuses in Afghanistan, including possible atrocities by American forces, must go ahead.

"This is a truly breathtaking action by an unaccountable political institution masquerading as a legal body," Pompeo told a news conference following the ruling at the International Criminal Court in The Hague. "All the more reckless for this ruling to come just days after the United States signed a historic peace deal on Afghanistan, which is the best chance for peace in a generation."

Pre-trial judges at the ICC had last year rejected a demand by its chief prosecutor to open a full-blown probe into alleged war crimes committed in the war-torn nation.

Prosecutors at The Hague appealed the move, saying the judges had erred by saying the request was "not in the interest of justice," and the appeals judges agreed with the prosecution.

The US government bitterly opposes the probe. "We're going to take all the appropriate actions to ensure that American citizens are not hauled before this political body to settle a political vendetta," Pompeo said, with an announcement to be made in the coming weeks.

ICC prosecutors previously said their investigation would include alleged war crimes by US Central Intelligence Agency operatives at detention facilities, referred to as "black sites" in ICC member countries like Lithuania, Poland and Romania.

At least 24 suspects were subjected to torture at these secret prisons between 2003-2004, the prosecutors said. The ICC move, which overturned a previous court ruling, was hailed by human rights organizations as a "pivotal moment" for victims of the central Asian country's 18-year-war since the 2001 US invasion.