US vice president calls leaders of Hungary, Czech Republic

U.S. Vice President Joe Biden speaks during a media briefing after a meeting with Ukraine's Prime Minister Arseny Yatseniuk in Kiev April 22, 2014.

WASHINGTON - Vice President Joe Biden called the leaders of Hungary and the Czech Republic to reassure them of US support for NATO's collective defence agreement, the White House said late Saturday.

Biden also spoke about the Ukranian crisis with Czech Prime Minister Bohuslav Sobotka and Prime Minister Viktor Orban of Hungary, the White House said in statements.

In his call to Sobotka, Biden "underscored the ironclad commitment of the United States to the collective defence of NATO under Article 5." He made similar remarks in the call to Orban.

Biden and Sobotka "agreed that Russia would face further costs for its destabilizing actions in Ukraine and massing of troops along the Russian-Ukrainian border." Biden and Orban also "discussed the need to strengthen the energy security of the Euro-Atlantic community with a more coordinated and strategic approach." In both calls Biden reiterated that Washington and its allies should be prepared to impose sanctions on Russian individuals and entities if Moscow further intervenes militarily in Ukraine.

Both countries, former satellites of the defunct Soviet Union, have been nervous as they see Russian intervention in Ukraine.

Both the Czech Republic and Hungary joined the North Atlantic Treaty Organisation - a group originally formed to counter the Soviet Union - in 1999.