She flew to Syria without telling anyone, to show support for Assad

while trashing our allies in the region, upending U.S. foreign policy, shortly after Trump took office:
https://www.theguardian.com/us-news/2017/jan/26/tulsi-gabbard-bashar-al-assad-syria-democrats

Russia wants Syria as an oil pipeline route to the sea and views Assad as an ally.

Recall that Gabbard quit the DNC in a public spat with DWS at a critical juncture in the Sanders/Clinton battle, playing up the favoritism the DNC appeared to show Clinton. That drove a wedge between two factions of Democrats and prolonged the bitterness and distrust, helping to depress enthusiasm for Democrats in the general, which again happens to be what Putin wanted.

Now couple that with Russia boosting Gabbard, like they did with Jill Stein, and a picture starts to emerge.
https://www.nbcnews.com/politics/2020-election/russia-s-propaganda-machine-discovers-2020-democratic-candidate-tulsi-gabbard-n964261

Gabbard has a fine background and appearance but acts as though she were an asset of Russia. Certainly the Russians defend her like one.