The Prime Minister is travelling to Warsaw on Thursday to discuss a new defence pact but she is flying into the middle of a row between Poland and the rest of the EU.
The European Union has triggered a process that could see Poland lose its voting rights over EU concerns about changes being made to its judicial system.
Theresa May says she will raise the issue and will have to find a diplomatic line between the views of her EU negotiating partners and those of member-state Poland, with whom Mrs May is trying to forge a new relationship.
The annual summit is designed to strengthen ties between the UK and Poland with the announcement of a new treaty of defence and security cooperation between the two countries which will include measures to tackle cyber attacks from Russia.
This builds on the deployment of British troops to Poland under Enhanced Forward Presence, agreed at the last UK-Poland summit held in London in November 2016.
Ahead of the trip, Mrs May said: “The bilateral defence treaty we are signing today is a powerful symbol of our continued close cooperation.”
“I am determined that Brexit will not weaken our relationship with Poland. Rather, it will serve as a catalyst to strengthen it.”
But the PM is certain to become embroiled in the row between Poland and the EU.
The Polish government is accused of putting forward legislation that will allow political interference in its court system.
The EU has issued a formal warning that could not only see Poland’s voting rights suspended but also a freeze on financial contributions to the bloc’s largest beneficiary.
Warsaw shows no sign of backing down and may look to departing EU member the UK for support against what it sees as a politically-motivated attack.
Mrs May was no doubt hoping for an uncomplicated pre-Christmas announcement about boosting defence cooperation in areas such as training, exercises, information sharing, and capability development.
The bilateral summit will bring together both Prime Ministers along with a number of senior Cabinet ministers, including the Chancellor, Foreign Secretary, Defence Secretary, Home Secretary and Business Secretary.
The Prime Minister is set to agree improved UK-Poland cooperation to counter Russian disinformation in the region, including through new joint strategic communications projects.
The UK will provide £5m for the project, with Poland expected to contribute a similar amount.
It will aim to build capacities to detect and counter Russian information operations, and deliver support to Belsat, a Polish-funded TV channel providing unbiased, free and frank reporting for Belarusians.
The UK will also host a Polish cyber delegation at our National Cyber Security Centre in March next year.
The Prime Minister said: “Poland matters greatly to the UK. Our partnership is broad, vibrant and diverse and we both share a steadfast commitment to Europe’s security and defence.
“Although the UK is leaving the European Union, we are not leaving Europe, and I will reaffirm to Prime Minister Morawiecki that we want to work with Poland and the other member states in the future to protect our shared values, people and interests.
“We are building a strategic partnership from a base of shared history and deep ties of friendship that will continue to flourish long after our departure from the EU.”