Washington - (AFP) - US President Joe Biden said Friday that Russian President Vladimir Putin will not "terrorize" the United States and its allies, warning that NATO will defend "every inch" of its territory.

"America and its allies will not be intimidated," Biden said in an intervention at the White House. "(Putin) will not intimidate us." Then he turned to the Russian president, saying, "America is fully prepared, with our NATO allies, to defend every inch of NATO territory (...) Mr. Putin, don't misunderstand what I'm saying, every inch."

The US President was speaking shortly after Putin officially signed a decision to annex four Ukrainian regions occupied by Russian forces, then promised him to achieve "victory" from Red Square in Moscow.

Biden described Friday's ceremony in the Kremlin as "vulgar" and aimed to show Putin's strength, but in fact proved "that he is in a difficult situation."

And touching on new aid to Ukraine worth $12 billion approved by Congress, Biden promised to "continue to provide military equipment" to this country "so that it can defend itself."

Likewise, he promised to send all the necessary equipment to the site of the explosions that affected the Nord Stream 1 and 2 pipelines to "determine what actually happened," after he described what happened as a "deliberate act of sabotage."

"We will work with our allies to uncover everything that happened. I have begun to help our allies strengthen the protection of these critical infrastructures," he said.