UK foreign secretary Boris Johnson has expressed regret over US President Donald Trump's decision to nix the Iran nuclear deal.

Johnson wrote on his Twitter account:  "Deeply regret US decision to withdraw from the Iran nuclear deal. UK remains strongly committed to the JCPOA, and will work with E3 partners and the other parties to the deal to maintain it. Await more detail on US plan."

US President Donald Trump announced on Tuesday that Washington is pulling out of the nuclear deal and reinstating nuclear-related sanctions on Iran.

This is while all other signatories to the JCPOA, including Russia, China, Germany, France, Britain, and the European Union have repeatedly stressed that keeping the deal is in the interest of world peace and security.