Increased membership fees for the alliance's member countries are expected to be the major main issue at the meeting in the Netherlands, led by NATO's Secretary-General Mark Rutte.
Sweden is represented by Prime Minister Ulf Kristersson (M).
Trump participated in NATO's top meeting in the spring of 2017 in Brussels, when Jens Stoltenberg was Secretary-General. Then, he scolded several of the other heads of state and government for not allocating enough money to their defense forces.
He had already pointed out Germany's then-Chancellor Angela Merkel, accusing Germany of owing NATO "large sums".
Then, the criticism concerned the established two percent of GDP that they should allocate to their defense forces – a percentage that is now considered too low.
NATO diplomats are said to have prepared the meeting in detail on June 24-26 to avoid new public clashes between member countries.