WASHINGTON, March 29 (Xinhua) -- U.S. State Department tweeted on Thursday that Russia's earlier decision to expel 60 U.S. diplomats was a "regrettable, unwarranted" one.

"It is clear that Russia is not interested in dialogue about issues that matter to our two countries," the State Department tweeted.

It added that Moscow "is further isolating itself" with its expulsion action following the poison attack in Britain against an ex Russian intelligence official and his daughter.

The Russian Foreign Ministry announced earlier on Thursday to expel 60 U.S. diplomats and close U.S. consulate in St. Petersburg in tit-for-tat retaliation for Washington's moves against Moscow over an alleged ex-spy poisoning incident. The 60 diplomats must leave Russia by April 5.

Speaking of the incident, U.S. State Department spokesperson Heather Nauert responded in a press release that there is "no justification" for Russia's expulsion decision, and by doing this Moscow will further isolate itself economically and diplomatically.

Noting that Russia shall not act like a victim, she added that the United States is reviewing the details of the Russian action and reserves the right to respond to Russian's action "accordingly."

Nauert said that 28 countries have jointed the United States to kick out 153 Russian officials from these countries.

Washington earlier this week expelled Russia diplomats on Monday in response to the poisoning attack of former Russian double agent Skripal and his daughter in Britain's southwestern city of Salisbury on March 4.

In his protest, Russia Ambassador to the United States Anatoly Antonov said on Monday that Moscow will give adequate response with regard to each case in the coming days.

Russian Foreign Ministry also said later that the West's expulsion of its diplomats is an unfriendly step, and vowed to react to it accordingly.

Russia has denied involvement in poisoning of the former spy and his daughter.