The United States warned Tuesday that Russia is “stepping up efforts to launch strikes against Ukraine’s civilian infrastructure and government facilities in the coming days.”

The message posted by the U.S. Embassy in Kyiv followed similar warnings from Ukrainian President Volodymyr Zelenskyy about potential Russian actions against Ukraine coinciding with his country’s Independence Day.

“Russian strikes in Ukraine pose a continued threat to civilians and civilian infrastructure,” the U.S. Embassy said, adding that U.S. citizens should depart Ukraine if they are able.

Wednesday marks 31 years since Ukraine gained independence from Soviet rule, as well as six months since Russia launched its war.

Amid the warnings, Kyiv canceled public Independence Day celebrations.

Poland’s President Andrzej Duda traveled Tuesday to Kyiv for talks with Zelenskyy and other officials about military, economic and humanitarian support for Ukraine.

The head of Duda’s office, Pawel Szrot, told reporters the neighboring leaders would also discuss “how Poland can politically help to persuade other countries to help.”

Elsewhere in the country, Ukraine’s military said Tuesday that Russian forces carried out fresh artillery and airstrikes in the Zaporizhzhia region where fighting has raised concerns about safety near Europe’s largest nuclear power plant.

Ukrainian casualties

Ukraine’s military chief said Monday nearly 9,000 soldiers have died since Russia invaded Ukraine almost six months ago.

General Valerii Zaluzhnyi made the remarks at a veterans event, giving the first official toll of Ukraine’s military losses since April.

The United Nations says it has confirmed the deaths of more than 5,500 civilians during Russia’s invasion of Ukraine, which began February 24.

The U.N. children’s agency said Monday it has confirmed at least 972 Ukrainian children killed or injured from violence but said the true number is likely to be much higher.

Most of the child casualties have been caused by the use of explosive weapons, according to a statement by UNICEF Executive Director Catherine Russell.

Some information for this story came from The Associated Press, Agence France-Presse and Reuters.