The United States has historically been a strong partner in cyber diplomacy for the EU based on common values (human rights, rule of law), goals (open, stable and secure cyberspace) and interpretation of international law. Cyber diplomacy with the US has also been operationalised in the form of information-sharing and cooperation to tackle cybercrime, cooperation on cyber defence via NATO and cyber capacity building in third countries. Despite differences over certain foreign policy issues, the EU and the US remain close allies in cyberspace.

The US believes that international law is applicable in cyberspace. As part of the ‘like-minded’ coalition, the US recognises a need to acknowledge the full breadth of relevant international law, including international humanitarian law (IHL), human rights law, customary international law on the responsibilities of states for internationally wrongful acts. The general applicability of IHL in cyberspace is not to be misconstrued as a tacit endorsement of aggression in the cyber domain; instead, it only serves to remind states of the responsibility to respect and protect civilians in the event of armed conflict. 
In the context of multilateral fora, US diplomats have specifically emphasised the applicability of the right to self-defence under Art. 51 of the UN Charter, noting that a State may lawfully take cyber-based or non-cyber-based countermeasures in response to internationally wrongful cyber activities attributable to another State, but only subject to the requirements of the doctrine under international law and the principles of necessity and proportionality.

As stated in the 2018 National Security Strategy, the United States views voluntary, non-binding norms of state behaviour during peacetime as essential components of a framework of responsible State behaviour in cyberspace. The US has participated in all iterations of the UN Group of Governmental Experts (UNGGE) as well as the latest Open-Ended Working Group.
In these multilateral fora, US diplomats have typically opposed attempts at shifting to a legally binding status for norms of responsible state behaviour, arguing that such discussions are “premature” and do not represent the best way to address the immediate threats given the fast pace of technological developments. 
The starting basis for any further discussions on the part of the US rests on the current buildup of consensus surrounding the norms identified in the 2015 and 2021 GGE reports. Efforts should be concentrated on the implementation of existing consensus norms, not the creation of entirely new normative concepts (i.e. in relation to harmful hidden functions and specific critical infrastructure sectors).

The March 2021 Interim National Security Strategic Guidance states that “[the US] will make cybersecurity a top priority, strengthening our capability, readiness, and resilience in cyberspace.” Following the recommendations of the 2020 Solarium Commission, the US government has adopted the concept of ‘layered resilience’ and is gradually rolling out a comprehensive arsenal of resilience measures across a variety of domains. 
The US has been active in engaging in strategically-minded capacity building with partners; US capacity building in Africa with organisations such as the African Union and SADC, for instance, have been largely motivated by Washington’s wish to promote an open, secure, and democratic model for Internet governance across the African continent. 
In relation to cyber defence, there have been several joint operations and military exercises, both bilaterally (e.g. between the US Cyber Command and the Montenegrin military) and under the auspices of NATO. Recent regional engagement efforts such as the dialogues in the context of the tripartite AUKUS coalition and the Structured Quadrilateral Security Dialogue (the eponymous Quad) also heavily feature references to collaborative cyber-capacity building. In multilateral fora, the US has also welcomed the inclusion of confidence-building measures in the GGE reports and noted that, in order for CBMs to be useful, they need to be implemented at minimum on a bilateral basis and preferably on a multilateral and eventually an international basis.

The US is a signatory and an early proponent of the Budapest Convention. A big part of American cyber diplomatic activity has, in fact, been focused on promoting the Budapest regime as the global model of cybercrime governance. In 2019, the US firmly opposed the Russian-sponsored resolution calling for an alternative legal instrument to the Convention; following the passing of the resolution, however, the US has agreed to participate in the Ad Hoc Committee established under UNGA resolution 74/247 despite the fact that the “surprise text” within the May 2021 resolution was seen as an effort to “circumvent dialogue” and undermine the “balanced, inclusive, consensus-based process” sought by the US. 
On a multilateral level, the US is also a party to the UN Convention against Transnational Organised Crime (UNTOC) and the Inter-American Convention on Mutual Legal Assistance of the Organisation of American States (OAS) and is a member of Interpol. 
Bilaterally, the US has completed an agreement with the UK under the CLOUD Act that facilitates cross-border data sharing directly between US companies and the British government; the US is trying to expand this type of bilateral engagement, currently negotiating a similar agreement with Australia.