On the ground: A column of Russian vehicles, and soldiers without insignia.

ROSTOV-ON-DON, Russia — Multiple military vehicles and soldiers with no insignia were seen parked on highways on Monday, in the vicinity of Rostov-on-Don, a major Russian city about 60 miles from the border with Ukraine.

Dozens of soldiers, some of them wearing balaclavas, walked around the equipment, which was parked in a one-mile-long column.

In an ominous sign, the military vehicles had no license plates, and the soldiers had all their insignia including names and military ranks removed from their uniforms. Some of the soldiers wore white ribbons on their shoulders.

Over the past weeks, military experts and investigators have traced mass movement of troops and equipment toward the Ukrainian border from Russia’s interior. They relied on witnesses, who posted videos of such moves on Tik Tok and other social networks.

In 2014, Russia dispatched a group of soldiers to lay groundwork for the annexation of Crimea in Ukraine. These soldiers wore no insignia, and while Moscow denied that the “little green men,” as they became known at the time, were in fact Russian soldiers, President Vladimir V. Putin eventually confirmed their presence on the peninsula.

Another column, consisting of missile systems covered in cloth, were spotted on the Don highway, along the Ukrainian border, that links Moscow with the Black Sea. Multiple groups of military trucks were also observed driving along that highway.

Members of law enforcement in Russia’s Rostov region increased security measures at train stations and border crossing points, where refugees, fleeing what they said was an increasingly tense situation in the breakaway republics, were processed before being sent to other cities across Russia on trains.

In a further escalation, the head of Russia’s Federal Security Service said in a meeting with Mr. Putin and top-level security officials that two groups of “saboteurs” tried to penetrate Russia in the Rostov region.

At the meeting with Mr. Putin, Russian security officials pointed to the situation with the “saboteurs” and also with the refugees, fleeing two separatist republics, as one of the main reasons for Moscow to move forward with formal recognition of the two separatist entities.

Oleksiy Reznikov, the Ukrainian minister of defense, called the situation with refugees “a farce.”

“It is just a production for Mosfilm,” he said, referring to a Russian film production company.

At a vast makeshift refugee processing center in Taganrog, Yelena Reznichenko, who is from the Ukrainian city of Debaltsevo, said that “she wants to go home,” but she feels that she “doesn’t believe government officials can make a deal” to avoid war.

“We don’t have anyone in Russia,” said Ms. Reznichenko. “I don’t know where we will go.”