Polish Prime Minister Donald Tusk has vowed to use his country’s presidency of the European Union to push forward with Ukraine’s membership quest.

The chairman of Ukraine’s parliament has offered words of reconciliation over World War II-era mass murders that have strained relations with its neighbor and strategic ally Poland for 80 years.

The heads of nine central and eastern European NATO members issued a joint statement backing a path to membership for Ukraine in the U.S.-led security alliance.