Venezuela's opposition leader Juan Guaido was mobbed by supporters, media and the ambassadors of allied countries as he returned to Caracas on Monday, defying the threat of arrest from embattled President Nicolas Maduro's regime.
Just before his arrival, US Vice President Mike Pence sent a warning to Maduro to ensure Guaido's safety.
"Any threats, violence, or intimidation against him will not be tolerated & will be met with swift response," Pence wrote on Twitter.
Thousands of flag-waving Venezuelans had already answered a call from Guaido, recognized as interim president by more than 50 countries, to take to the streets and protest against Maduro, whom he is trying to oust.
In a video shared on social networks, Guaido warned that if Maduro's government "tries to kidnap us ... it will be one of the last mistakes it makes."
The self-declared acting president added on Twitter that should he be detained, he has left "clear instructions to our international allies and parliamentary brothers."
"The challenge has gone very far," political analyst Luis Salamanca told AFP. "If he comes in and they stop him, it will generate strong internal reaction as well as internationally. Maduro is at permanent risk."
European Union foreign policy chief Federica Mogherini warned Maduro on Saturday that detaining Guaido would incur "a major escalation of tensions."