Polish President Andrzej Duda made an unannounced visit to meet with President Volodymyr Zelensky on June 28, the Polish president's office reported.
Duda will meet with Zelensky on the sidelines of the 27th-anniversary of Ukraine's Constitution to discuss the ongoing situation on the frontline, including the threat of a Russian attack on the Zaporizhzhia nuclear power plant.
On June 23, Ukraine's military intelligence chief Kyrylo Budanov said that Russia had completed preparations for an attack on the nuclear plant and had mined the plant's cooler. Lubinets also warned that there was a "real possibility" of an attack taking place.
The International Atomic Energy Agency, however, has said that no new mines were discovered during a recent visit by its chief Rafael Grossi. The White House has also said it sees no nuclear threat in Ukraine at the moment.
The Institute for the Study of War, a D.C.-based think tank has assessed that Russia may be signaling that is willing to carry out an attack to dissuade Ukraine from attempting counteroffensive operations in the area.
Duda will also discuss the agenda of the upcoming NATO summit in Vilnius, according to Poland's president's office.
NATO's 31 member states will meet in Vilnius in July to discuss a number of issues, including potential security guarantees for Ukraine, Sweden's entrance into the alliance, and Stoltenberg's possible successor.
Earlier on June 28, Lithuanian President Gitanas Nauseda also arrived for an unannounced visit to Kyiv to meet Zelensky and discuss the agenda of the upcoming NATO summit in Vilnius with Zelensky, Ukraine's membership in the European Union, as well as Lithuanian and European Union aid to the country.