UK military trainers will be sent to Jordan to help the nation's air force in the fight against Islamic State, Theresa May will announce during a visit to the Middle East.
After the Westminster terror attack, the Prime Minister will say the threat posed by the jihadi group shows how allies must come together to face it down.
Arriving in Amman on Monday, she will set out a package of measures to bolster co-operation between British forces and the Royal Jordanian Air Force (RJAF) and to tackle violent extremism in the region.
Jordan has stepped up its air strikes against IS, also known as Daesh, in recent months and boosting military links with the nation will help keep Britain safe, the PM will say.
Training will be carried out in Jordan and the UK to help the RJAF improve its capability to strike IS targets.
During talks with King Abdullah a month after they met in Downing Street, the premier will also discuss support for the state as it deals with the fall-out from the conflict in neighbouring Syria, which has forced hundreds of thousands of refugees to flee over the border.
The Prime Minister is also heading to Saudi Arabia during the three-day trip, which will focus on strengthening trade and security ties as Britain prepares to quit the European Union.
Ahead of the visit, she said: "As the United Kingdom leaves the EU, we are determined to forge a bold, confident future for ourselves in the world.
"We must look at the challenges that we, and future generations, will face and build stronger partnerships with countries that will be vital to both our security and our prosperity.
"It is clearly in the UK's security and prosperity interests to support Jordan and Saudi Arabia in tackling regional challenges to create a more stable region, and in delivering their ambitious reform programmes to ensure their own stability.
"An even deeper partnership with these countries, and greater knowledge and understanding of one another, will increase our ability to address the issues that concern us, including the promotion of international standards and norms.
"To tackle the threats we face from terrorism and from geopolitical instability, we must meet them at their source.
"Jordan is on the frontline of multiple regional crises and I'm clear that by working with them, we are helping keep British people safe.
"Likewise in Saudi Arabia: we must never forget that intelligence we have received in the past from that country has saved potentially hundreds of lives in the UK.
"And there is so much we can do together on trade, with immense potential for Saudi investment to provide a boost to the British economy.
"So I hope my visit will herald a further intensification in relations between our countries and deepen true strategic partnerships, enabling us to seize the opportunities ahead and ensure the security and prosperity of our people for decades to come."
On Tuesday, she will fly to Saudi Arabia - the UK's largest trading partner in the Middle East, with goods and services exports totalling £6.6 billion in 2015 - where talks will focus on stronger ties following the vote for Brexit.
Mrs May has faced repeated calls to suspend arms sales to Riyadh amid claims of widespread human rights abuses in Yemen during the coalition bombing campaign it is leading, which includes Jordan.
The Saudis back the war-torn country's internationally recognised government against Iran-backed Houthi rebels.
Britain has continued to allow arms sales, with more than £3.3 billion of exports since the bombing began in March 2015. At least 10,000 people have been killed during the war, according to the United Nations.
Foreign Secretary Boris Johnson apologised at the weekend to the Saudi government after an activist in London tried to carry out a citizen's arrest of one of the Gulf state's generals.
An anti-war campaigner attempted to arrest Major General Ahmed Asiri over Saudi Arabia's involvement in the conflict in Yemen, while another protester threw an egg at the senior officer as he arrived at an event.
Mr Johnson "expressed his regret" at the incident during a phone call with Deputy Crown Prince Mohammed bin Salman.
There could be further embarrassment after the Metropolitan Police said its war crimes unit was considering an investigation into Saudi activities in Yemen.
A Met spokesman said: "On Thursday 30 March 2017, the Metropolitan Police Service (MPS) received a referral of an allegation of war crimes, made against Saudi Arabia, committed in Yemen.
"Following receipt of the referral, the MPS war crimes team (part of the Counter Terrorism Command) began a scoping exercise and contacted those making the allegations.
"There is no investigation at this time, and the scoping exercise continues."
The Saudi visit comes days after the Government was pressed to explain why the state "consistently features in the back story of terrorists" - including the Westminster attacker.
Khalid Masood, the extremist who carried out the 82-second rampage on March 22, worked in the country for several years.
The Kent-born 52-year-old mounted the kerb twice as he sped across Westminster Bridge, killing three people and leaving dozens injured, before charging the Palace of Westminster grounds armed with two knives, killing Pc Keith Palmer.