The Prime Minister is travelling to the Middle East to hold talks on the fight against so-called Islamic State, tackling the Syrian refugee crisis and building on relations with Britain after the UK leaves the EU.
First she will visit Jordan where she is set to announce that UK military trainers will be sent to the country to help the nation's air force in the fight against the so-called Islamic State.
After the Westminster terror attack, Theresa May will say the threat posed by the group shows how allies must come together to face it down.
Arriving in the capital Amman on Monday, she will set out measures to tackle violent extremism in the region and strengthen co-operation between British forces and the Royal Jordanian Air Force (RJAF).
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 the premier will also discuss humanitarian support as it deals with large numbers of refugees who have fled over the border from the Syrian conflict.
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 leave the European Union, days after triggering Article 50. The country is the UK's largest trading partner in the Middle East, with goods and services exports totaling £6.6 billion in 2015.
Speaking ahead of her 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."