US National Security Advisor John Bolton said Monday that Washington wanted "to move very quickly" on a trade deal with Britain after it leaves the EU, and that the White House would wait

until after Brexit to address various security concerns.

The hawkish White House aide spoke in London after becoming the most senior official from Donald Trump's administration to meet Prime Minister Boris Johnson since he succeeded Theresa May as UK government leader last month.

"We want to move very quickly. We wish we could have moved further along in this with the prior government" Bolton said of a potential trade deal.

"The message I wanted to convey on Iran, and on some other issues in which I include China, 5G, Huawei, that cluster of issues, is that the President and the US government fully understands that in the next few days the UK government has a singular focus on the Brexit issue," he said.

Bolton said he had received reassurances from Johnson that Britain was "concerned about not having any compromise in the security of telecommunications in the 5G space."

"There will be time enough to talk, that is really all we ask for."

The meeting came with Trump's administration pursuing a "maximum pressure" campaign designed to force Iran to limit nuclear and military activities.

- Uncertain future -

Bolton arrived in a Britain wracked by political crisis and with the pound straddling multi-year lows as the deadline approaches for it to leave the EU after more than 40 years.

Johnson has vowed to meet the twice-delayed Brexit date -- now October 31 -- even if it means leaving without a proper plan to regulate trade and other ties.

Senior UK economic officials and big industries warn that this "no-deal Brexit" option could create border chaos and set off global financial tremors in the short term.

The EU is refusing to re-open negotiations on the deal the bloc's 27 leaders signed last year with May. Johnson and his supporters call the existing agreement unfair.

But a clean break with the EU would allow the UK to immediately launch negotiations on a free trade agreement with the United States.

Trump openly rooted for Johnson during his campaign for May's job following her resignation over the Brexit impasse.

The US president branded Johnson as Britain's Trump and said the sides were on the verge of making a breakthrough in ties.

Britain and its European allies have irritated Trump's team by trying to save a landmark nuclear agreement with Iran which Washington pulled out of last year.

Britain last week decided to join forces with the US to protect merchant vessels in the Gulf.

It marked a departure in policy for Johnson following May's attempts to form a European-led group.

Britain's decision on Huawei -- a private firm that Washington claims is obliged to spy for the Chinese government -- has been repeatedly delayed due to mixed signals from Trump about his own administration's next steps.

Johnson's spokesman said the UK government was "still assessing the impact" of Trump's decision in May to effectively ban Huawei from trading with US firms.afp, foto by Michael Vadon