The Democrats are suddenly concerned about Russia as an enemy now that Donald Trump has assumed the office of the presidency. But they seem to have experienced collective amnesia about their party's habit of selling out the United States to Russia time and time again.

Here are five times the Democrats have done so.

1. Barack Obama told the Russians in 2012 he will "have more flexibility" after the election. Here was the conversation between Obama and then-Russian president Dmitry Medvedev (H/T: The Weekly Standard):

President Obama: "On all these issues, but particularly missile defense, this, this can be solved but it’s important for him to give me space."

President Medvedev: "Yeah, I understand. I understand your message about space. Space for you…"

President Obama: "This is my last election. After my election I have more flexibility."

President Medvedev: "I understand. I will transmit this information to Vladimir, and I stand with you."

Once Obama won re-election, he basically allowed current Russian president Vladimir Putin to wreak havoc in the region without much pushback, despite Obama's tough talk against him.

2. Hillary Clinton gave at least 20 percent of the United States's uranium stockpile to the Russians as secretary of state. Clinton allowed the sale of Uranium One to the Russian government during her tenure as secretary of state, giving the Russians at least 20 percent of the U.S.'s uranium output, maybe even as much as 50 percent.

3. Obama ignored the Russians hacking their infrastructure to obtain a deal over Syria in 2013. The deal essentially cemented Syrian dictator Bashar al-Assad's grip on power, embarrassing the U.S. after Obama failed to follow through on his "red line" when Assad used chemical weapons against his own people. The deal also sealed Putin's status as the man calling the shots in the Middle East. Meanwhile, Russia's hacking efforts at the time received no pushback from Obama, setting the stage for the 2016 hacks of the Democratic National Committee and Clinton campaign chairman John Podesta's email server.

4. Former Sen. Ted Kennedy (D-MA) offered the Soviets a deal to undermine Ronald Reagan's foreign policy. The Daily Wire reports:

The former Massachusetts senator proposed to help established interviews between Moscow and various American TV outlets in order to make the Soviet Union's "peaceful intentions" well-known. Kennedy hoped that this would weaken Reagan's foreign policy toward the Soviet Union; hence setting up an opening for Kennedy to challenge Reagan in 1984.

It is not known if the Soviets ever accepted Kennedy's proposal.

5. John F. Kennedy made a secret deal with the Soviet Union during the Cuban Missile Crisis. According to the History News Network, the stage for the Cuban Missile Crisis was set when Kennedy botched the Bay of Pigs invasion to assassinate Fidel Castro. After the Soviet Union realized that Kennedy was a pager tiger that would fold in the face of Soviet aggression, Soviet dictator Nikita Khruschev began funneling nuclear missiles to Cuba, knowing that Kennedy would be reluctant to fight back. When the U.S. discovered this activity, a deal was hammered out where the Soviets would remove the missiles from Cuba if the U.S. removed nuclear missiles from Turkey and promised to never invade Cuba. The former was the secret part of the deal; it was exactly what the Soviets were aiming for and they got it, even though they were negotiating from a position of weakness.

Follow Aaron Bandler on Twitter.