Sudan's President Omar al-Bashir is threatening war against South Sudan, as fighting continues along the two countries' border.

On Wednesday, President Bashir vowed to crush South Sudan's government, likening the south's ruling SPLM party to an insect.

Addressing another rally Thursday, he said Sudan will teach the south's government “a lesson by force,” and vowed to retake the oil-producing town of Heglig, which southern forces occupied last week.

He added that “Heglig is not the end, but the beginning.”

The U.S., China, and other world powers have called on Sudan and South Sudan to stop fighting and resume peace talks — so far with little effect.

The countries' troops battled Tuesday night near the town of Meiram, located in Sudan's Southern Kordofan state. South Sudan's military spokesman, Philip Aguer, reported more fighting along the border Thursday.

The two countries have been unable to resolve disputes over borders, oil, and citizenship issues stemming from the south's independence last July.

South Sudan shut down all oil production because of a dispute over transit fees to use the north's pipeline and port.

Starting in the 1980s, north and south Sudan fought a 21-year civil war that eventually led to southern autonomy and independence.

Currently, Sudan is demanding the south withdraw from Heglig, while the south has condemned Sudan for a series of airstrikes.

The countries have also accused each other of supporting rebels on each other's territory.