MOSCOW, March 21 (Xinhua) -- Russian President Vladimir Putin on Friday signed into law legislation on the accession of Crimea while toning down possible retaliatory measures against the U.S. sanctions on Russia.

Putin signed the law after both houses of the parliament unanimously approved it.

"I signed several decrees today, including the decree on the formation of one more federal district, the Crimean federal district," Putin said following the ceremony on signing the decree on the accession.

"We have a lot of work ahead on Crimea's adaptation and on its joining Russia's legal system, the Russian economy and the social sphere," Putin added.

According to a treaty approved by the Federation Council, or the upper house of the parliament, the accession was based on "free and voluntary expression of will" of the Crimean people at an all-Crimea referendum held on March 16, during which the Crimean people decided to reunite with Russia.

Russia guarantees the Crimean people's right to preserve their native language and pledges to create conditions for the native language studies. Russian, Ukrainian and Crimean Tatar become state languages of Crimea.

Following the signing ceremony, Putin appointed Oleg Vladimirovich Bulavintsev as presidential envoy in Crimea, urging both houses of the Russian parliament to facilitate the accession of Crimea and Sevastopol to Russia.

"I request deputies of both houses to actively engage in this work and do everything that depends on you to make this process not only seamless, but also beneficial for all Russia and for Crimean residents," he said.

During a separate meeting with members of the Security Council, Putin said Russia was not going to hastily adopt sanctions against the United States or introduce visa restriction with Ukraine.

"In case we introduce visa regime with Ukraine, millions of innocent Ukrainians will suffer. We don't need to do that," Putin noted.

Speaking about current situation in Crimea, Putin demanded that Ukrainian state and military symbols in the peninsula be respected.

The president ordered Defense Minister Sergei Shoigu to take care of these symbols and the Ukrainian servicemen who would opt to stay faithful to Kiev authorities.

According to Shoigu, 72 units of Ukraine's armed forces in Crimea have voluntarily raised Russian flags on Thursday.

During the same meeting, Putin decided to transfer his salary to the Rossija (Russia) bank, which fell under U.S. sanctions because two of its shareholders appeared in Washington's blacklist.

"I'm going to open there my personal account on Monday and I've ordered that my salary will be deposited there," Interfax news agency quoted Putin as saying.

He noted that the bank and its clients had nothing to do with the events in Ukraine and ordered the Central Bank to support Rossija, "especially because it bears such a nice name."

Later in the day, Russian Foreign Ministry showed a tougher position, with its spokesperson Alexander Lukashevich warning that the country would adopt tit-for-tat measures against the U.S. sanctions.

"Washington should have no illusions: the sanctions' effectiveness from the viewpoint of American interests is equal to zero. But the irresponsible actions will inevitably harm Russian-American relations," he said.

"We are certain to respond toughly as already happened on more than one occasion earlier with respect to previous sanctions," the diplomat added.