Financial Times | Guy Chazan and Najmeh Bozorgmehr:�European countries have stepped up the pressure over Iran�s ballistic missile programme and its role in regional conflicts as they struggle to respond to President Donald Trump�s threat to junk a landmark nuclear deal with Tehran.

The German, French and British foreign ministers � together with Federica Mogherini, the EU�s foreign policy chief � agreed with Iran to hold an �intensive and very serious dialogue� on Tehran�s missile programme and regional influence, the foreign ministry in Berlin said. Sigmar Gabriel, Germany�s foreign minister, briefed Rex Tillerson, his US counterpart, about the plan after the European officials met their Iranian counterpart Javad Zarif in Brussels last week.

That meeting took place a day before Mr Trump warned European signatories to the 2015 nuclear deal that it was their �last chance� to fix it, as he said he was extending a sanctions waiver for the final time.

Mr Trump has described the agreement as the �worst ever� and in October refused to recertify that Iran was in compliance with the accord, putting its future in limbo. He accuses Iran of stoking extremism across the Middle East and cites its ballistic missile programme � which does not fall under the nuclear deal � as a regional security threat.

Under the deal, which Iran signed with the US, UK, Germany, France, Russia and China, Tehran agreed to limit its nuclear activities in return for the lifting of many sanctions on the Islamic republic. European nations are desperate to protect the accord, which they consider an example of an international agreement easing a brewing global crisis.

Basically it�s an ultimatum to the EU. If you don�t deliver in the next four months, then you are part of doomsday � and you are siding with Iran European diplomat. � European diplomats are now urgently seeking more information from White House officials to understand exactly what Mr Trump wants and how they might be able to meet his demands by the president�s 120-day deadline.

�Basically it�s an ultimatum to the EU,� said one European diplomat. �If you don�t deliver in the next four months, then you are part of doomsday � and you are siding with Iran and not with us.�

Another diplomat said that �quite a lot� Mr Trump has pushed for �is already happening�. �We have got a reasonable amount of time to think it through, and talk to the Americans about what this is really about,��the diplomat said.

European diplomats point out that the EU has long expressed a willingness to take action over Iran�s non-nuclear activities, including its missile tests and its involvement in the conflict in Syria and other Middle East countries. But they also insist that it is impossible to change the terms of the nuclear deal without voiding it. Russia has criticised Mr Trump�s statement last week as extremely unhelpful.

Recommended Donald Trump waives Iran nuclear sanctions Europe calls on Trump to keep Iran deal alive Iran comes to Brussels Diplomats say they still need greater clarification on the details of the White House�s demands, although a US official has said discussions with Europeans are �quite advanced�.

A Trump administration official has said the demands include provisions for a pact with Europeans to impose new joint EU-US sanctions on Iran should it come within a year of having a nuclear weapon. Mr Trump has said he also wants a permanent mechanism to trigger sanctions if Iran tests long-range missiles or thwarts nuclear inspections.

Tehran has been trying to maintain good relations with Europe to prevent the formation of a broader international front against Islamic republic over its regional policies.�But Iranian analysts warn that without the US�s backing the nuclear deal cannot survive.