Updated at 3:59 p.m. ET
The FBI's arrests of 10 Russian spy suspects had to be carried out Sunday partly because one of the defendants was scheduled to leave the United States, a Justice Department spokesman said Tuesday.
Department spokesman Dean Boyd declined to identify which of the 10 defendants arrested Sunday was planning to exit the United States. Court documents indicate the FBI believed that defendant Anna Chapman was about to go to Moscow, but it was not clear that her impending departure was the one that triggered the arrests.
Boyd also said the arrests "had to be carried out Sunday for several critical law enforcement and operational reasons." He declined to identify all the reasons but said they included "the fact that one of the suspects was scheduled to depart the United States and had to be arrested before departure."
"These operational considerations were the only factors that dictated the timing of the arrests," Boyd added.
A senior Russian member of Parliament suggested Tuesday that elements of the U.S. government opposed to the recent thaw in U.S.-Russian relations were responsible for the timing of the arrests.
On Saturday at a restaurant in New York City, an FBI undercover agent posing as a Russian agent spoke with Chapman, according to court papers.
The FBI undercover agent told Chapman that "I know you are going back to Moscow in two weeks," the court document said. The FBI undercover agent added, "for now I just wanted to see how you are doing, how everything is going and then I have a task for you to do tomorrow." The arrests took place the next day.
In Moscow on Tuesday, Vladimir Kolesnikov, a deputy chairman of the security affairs committee in the lower house of parliament, told RIA Novosti the arrests signaled that some quarters in the U.S. government oppose warmer ties with Russia.
"Regrettably, there are people in America burdened by the legacy of the Cold War, the legacy of double standards," he said. "And they react improperly to the warming of relations spearheaded by the presidents. It's a blow to President Obama."
Kolesnikov, a former deputy prosecutor general, said "U.S. secret agents are continuing to work" in Russia and suggested that Russia could respond tit-for-tat.
"Previously we have quietly evicted some of them," he said. "Now I think we should more actively apply criminal legislation against them."
Kolesnikov is not believed to have close ties to the Kremlin or knowledge of the government's plans.
More on Spy Arrests
Obama Ducks Question on Alleged Russia Spy Ring
Russia: Spy Arrests a Throwback to Cold War
Russian Spy Ring Exposed
Accused Russian Spy a "Practiced Deceiver"
Ex-KGB: Russia May Have 50 Spy Couples in U.S.
11th Russian Spy Ring Suspect Arrested, Released
FBI: 10 Russian Spies Arrested in U.S.