Leonid Volkov said Putin has not met his international obligations before and any new agreements should take that into account.
The critic of Vladimir Putin had been on hunger strike since March 31 in protest at inadequate medical treatment at his prison.
Into his fourth week of a hunger strike, the opposition leader is languishing in a prison amid growing concerns for his life.
The opposition politician is three weeks into a hunger strike and fears are growing for his life, with his personal doctor having warned he could "die any minute."
Concern is growing for the fragile health of the opposition leader, who has been on hunger strike in prison for three weeks.
The Russian president said in his annual state-of-the-nation address that his country had been the victim of "illegal" sanctions.
"Russia has its own interests, which we will defend in line with the international law," Putin said.
Russian opposition leader Alexei Navalny, who is imprisoned and in the midst of a hunger strike, described himself on Tuesday in an Instagram post as "a skeleton" who "staggers around his cell."
John Sullivan has said he would leave Moscow and return to the U.S. as the countries imposed tit-for-tat sanctions.
The Kremlin critic has been transferred to a prison hospital in a colony his allies say is renowned for its brutality.
Russian Foreign Minister Sergey Lavrov suggested that John Sullivan, the U.S. ambassador to Russia, return to the United States to consult with the White House in a response to new sanctions the U.S. has placed on Russia.
As Russian opposition leader Alexei Navalny, 44, sits in prison amid an ongoing hunger strike, he used his Instagram account to say that he has been threatened with a straitjacket to be force-fed on Friday.
Concern for the jailed Russian opposition leader, who has been on a hunger strike since March 31, has been growing.
Dmitry Polyanskiy, Russia's UN envoy, said that sanctions on Moscow would be met with an "adequate response."
Sergei Ryabkov's comments come after Secretary of State Antony Blinken warned Moscow about acting "recklessly."
Anatoly Antonov said he was "deeply touched" by what he said were messages of support for the Russian leader from Americans.
The Russian leader has offered to meet his U.S. counterpart "in an open, direct discussion" as early as March 19.
The U.S. president caused a stir in Moscow by also telling ABC his Russian counterpart would "pay a price," for election meddling.
"Nobody is allowed to talk like that about our head of state," Vyacheslav Volodin said on the Telegram messenger app.
The report by the Office of the Director of National Intelligence found that Russia wanted to harm Joe Biden's candidacy.
Russian government watchdog Roskomnadzor accused Twitter of hosting illegal content and has slowed its access down to users.
"The government's task is to scare you and then persuade you that you are alone. Our Voldemort in his palace also wants me to feel cut off," Putin critic Alexei Navalny said Saturday.
Kremlin spokesman Dmitry Peskov said the Nord Stream 2 pipeline between Russia and Germany has "nothing to do" with the U.S.
The opposition politician has been jailed following protests across Russia, but his profile has exploded on social media.
Executive director of Navalny's anti-corruption foundation, Vladimir Ashurkov, told Newsweek that "support for Putin is ebbing."
The Levada Center survey found more Russians expected protests but that fewer wanted to attend them.
Yevgeny Agafonov was arrested in St. Petersburg despite not taking part in the protests in support of opposition leader Alexei Navalny.
Former U.S. ambassador to Moscow Michael McFaul told Newsweek that the U.S. should be not help the Russian opposition.
The Russian opposition leader had been arrested in Moscow upon arrival from Berlin where he had been treated for Novichok poisoning.