There are 76 Russian battalion tactical groups in Donbas and southeast Ukraine, eleven of them have joined in the last few days, a senior U.S. Department of Defense official said.

"There are now 76 Russian battalion tactical groups in the Donbas region of Ukraine and in the country's southeast. About eleven of those were added over the last several days, a senior Defense Department official said today," the Defense Department website said on Monday.

In addition to the 76 BTGs, there are about 22 BTGs north of Ukraine that are likely to be replenished and refitted, the official said.

He drew attention to the fact that about a dozen BTGs located inside Ukraine are trying to capture Mariupol. If Mariupol falls to the Russians, the official said, that would free up about a dozen BTGs for use elsewhere in eastern or southern Ukraine.

"It's a big if, because the Ukrainians are still fighting very, very hard for Mariupol," he said.

In addition, the official informed that the 155-mm howitzers of the U.S. Army and Marine Corps, which are in the U.S., are intended for Ukraine and will be sent soon. According to the official, since the Ukrainian Armed Forces are not familiar with this type of artillery, training of instructors will be organized for Ukrainians outside of Ukraine in the coming days.