The US government has moved to freeze the assets of three individuals suspected to be part of the Haqqani militant network.
The Treasury Department said Saidullah Jan, Yahya Haqqani and Muhammad Omar Zadran were now "specially designated global terrorists".
This means assets they have within US jurisdictions will be frozen.
The Pakistan-based militant network was designated a terrorist group by the US, making it subject to sanctions in 2012.
"The Haqqani network poses a grave threat to US civilians, military personnel and our broader interests in the Afghanistan-Pakistan region," said Under Secretary for Terrorism and Financial Intelligence David S Cohen.
"Where we have the opportunity to disrupt this network and undermine its ability to finance its activities, we will take action. Today's action underscores our resolve to continue targeting any potential means of support for the Haqqanis."
The order also prohibits US citizens from doing any business with these individuals.
Afghan intelligence officials say that the order will hurt the network and its operational capabilities, and could affect the flow of money into the group, the BBC's Bilal Sarwary reports from Kabul.
Our correspondent adds that according to intelligence sources in south-east Afghanistan these individuals were responsible for the taxation of local traders and contractors in Afghanistan and often helped to bring money in from the Gulf.
According to the US order:
- Saidullah Jan is a senior member of the Haqqani network who has also acted as an operational commander in Afghanistan, with responsibilities for recruitment
- Yahya Haqqani was responsible for the group's financial, military and propaganda activities
- Muhammad Omar Zadran is suspected of planning attacks against Afghan citizens and the Afghan government on behalf of the Haqqani network and the Taliban.
The US has long described the Haqqani group as a major threat. The network - which has links to al-Qaeda and the Taliban - has carried out a series of high-profile attacks against foreign troops in Afghanistan.