The sinking of a South Korean naval vessel Friday is raising fears that North Korea is once again rattling its sabers, though there is so far no evidence that Pyongyang had a role in the incident.

The South Korean ship, navigating in disputed waters in the Yellow Sea, was sunk Friday, and perhaps dozens of sailors were killed. But the cause of the sinking is unclear at time of writing.

Sketchy reports out of South Korea that a North Korean torpedo was used against the vessel were enough to raise the specter that North Korea is escalating tensions between the two countries. North Korea is seen as increasingly desperate – wanting to demonstrate its power to an international community hoping that sanctions will discourage Pyongyang from building nuclear missiles.

But there is scant evidence that North Korea in fact attacked the vessel.

Reuters news agency reported that a defense ministry official said the object the distressed vessel had fired on before it sank was actually a flock of birds. And Reuters quoted Kim Eun-hye at Blue House, the presidential residence in Seoul, as saying: “It is premature to discuss the cause of this sinking. It is not clear whether North Korea was involved.”

Still, South Korean officials were huddled to discuss the problem as crews were rescuing about 58 sailors left stranded by the sunken ship. Reports indicated that dozens of sailors may have died. US officials had no immediate comment on the sinking of the ship.

North Korea has been known to taunt the South, including the test of a missile device last year. Navies from both Koreas exchanged gunfire for the first time in seven years in the Yellow Sea waters in November, according to Reuters.

Though it’s far from clear that North Korea played any role in the ship's sinking, the North may be growing more desperate, seeking to reinforce an “existential threat” by playing it up internally.

“If you put all these pieces together, you can easily reach the conclusion that the regime is trying to reestablish its hold,” says Nicholas Szechenyi, a fellow at the Center for Strategic and International Studies, a think tank in Washington. “Creating the notion of an existential threat is one tool in their playbook.”

Mr. Szechenyi said it is too early to say what role North Korea played in the sinking of the ship. But if it is found to have targeted the ship, that would be a dramatic escalation, he said. “An attempt to sink a vessel would represent another level of tactical maneuver that we haven’t seen, and I think would be an escalatory step that is not in anyone’s interest.”