Mutual security guarantees are included when France and Poland sign a new strategic cooperation agreement.
If there is an attack on Poland or France, both countries promise each other mutual support, including military, says Tusk before departing for Friday's ceremony in Nancy in eastern France, reports news agency AFP.
According to Tusk, it also opens up for "discussions" about Poland being protected by France's nuclear.
Poland has heavily in recent years and is now the country in NATO that spends the most on its defense, in relation to its GDP. Numerically, Poland also has the military alliance's third largest defense after the USA and Turkey, with 216,000 personnel, according to NATO's annual report last year.
