"The Trump administration is continuing to review and develop its policy on Iran.no decision has been made", Tillerson said during the news conference.
But in the face of resistance from China and Russian Federation, the U.N. Security Council on Monday imposed only restrictions on the North's oil imports, among other sanctions.
'We will stand by our ally as Brexit continues to take shape. "We had hoped for a much stronger resolution from the Security Council". Merkel suggested that the approach taken with Iran - lifting global sanctions in exchange for it curbing nuclear activities - could be used with North Korea.
After Mrs May dropped into the No 10 meeting, her spokesman told reporters: '(They) touched on the Iran nuclear deal, the PM underlining its importance in preventing Iran from procuring nuclear weapons.
Tillerson Says Iran 'Clearly in Default' of Nuclear Deal's Terms
As part of the worldwide deal, the USA agreed to waive a wide range of sanctions on Iran and must renew the waiver every 120 days. The U.S. still maintains numerous sanctions against Iran over its ballistic-missile program and as a state sponsor of terrorism.
On North Korea, Mr Johnson said Pyongyang had "defied the world" adding that sanctions would be imposed in a way that maximised the pressure on the regime.
'They agreed on the importance of the worldwide community continuing to work together to put pressure on the regime'.
Thursday's talks in London also addressed the response to Hurricane Irma, which has caused havoc in the southeastern United States and the Caribbean, where Britain and France have dependent territories.
Friday's test comes just days after the passage by the United Nations Security Council (UNSC) of resolution 2375, which targets North Korea's textile industry, applies caps on the transfer of refined petroleum products and natural gas to the country, and blacklists three major DPRK government bodies.
And expect the situation in Libya to come up during talks with representatives from the U.N., Italy, Egypt and the United Arab Emirates. "Close coordination with our allies is vital for both the short-term and long-term recovery efforts", Johnson was quoted as saying Wednesday ahead of the meeting.