Ukraine President Volodymyr Zelensky is going to Washington DC to try to rescue a threatened US defence package to Kyiv worth billions of dollars.
The aid has become embroiled in US domestic, partisan politics.
It will be Mr Zelensky's third visit to the US since Russia's February 2022 invasion of Ukraine.
The week is a crucial one for Ukraine, with the European Union also deciding whether to open formal talks on its accession to the bloc.
Hungarian Prime Minister Viktor Orban has signalled that he opposes the move, and has the power to block such a decision.
Mr Orban and Mr Zelensky had an apparently intense conversation when they met on Sunday at the inauguration of Argentina's new president. The details of their discussion have not been revealed.
