In this Monday, Feb. 20, 2012 file photo, a Kenyan army soldier carries a rocket-propelled grenade launcher as he patrols in Tabda, inside Somalia. Kenya's military said Sept. 28, 2012 that its troops attacked Kismayo, the last remaining port city held by al-Shabab insurgents in Somalia. (Ben Curtis/AP)

Kenya’s military declared Friday that it had captured the last stronghold of Somalia’s al-Shabab militia, potentially crippling the al-Qaeda-linked group financially and forcing it to rely on insurgent and terrorist attacks to advance its agenda.

It remained unclear, however, how much of the port town of Kismayo the Kenyans actually controlled and whether they were facing resistance there from the al-Shabab fighters.

Maj. Emmanuel Chirchir, a spokesman for the Kenyan military, said Kenyan forces operating as part of an African Union effort to support the weak Somali government had entered Kismayo in a pre-dawn ocean assault dubbed Operation Sledge Hammer.

“Kismayo falls and under control,” Chirchir wrote on Twitter. “All forces in good shape and spirit.”

Al-Shabab said, also on Twitter, that it was fighting back against the Kenyan forces and maintained that “the courageous mujaheddin” were thwarting the invasion.

“Kismayo remains firmly in the hands of the mujaheddin, stay tuned for updates,” the militia wrote.

According to residents, Kenyan forces had taken control of the port but not the entire town. “Al-Shabab fighters are on the streets and heading toward the front line in speeding cars. Their radio is still on the air and reporting the war,” Mohamed Haji, a resident, told the Associated Press.

If Kismayo does fall, it would represent a significant military and financial blow to the militia, which still controls large swaths of the countryside in southern Somalia. The town, especially its port, is a significant source of the revenue the militia uses to finance its operations.

The assault on Kismayo comes nearly a year after U.S-backed African Union forces, mandated to help Somalia’s transitional government, pushed al-Shabab out of the capital, Mogadishu.

Since then, the militia also has withdrawn from other towns, offering little resistance to the African Union forces, including the Kenyan troops.

Kenyan forces entered Somalia last October following a spate of kidnappings and assaults inside Kenya, including some that targeted Westerners. The attacks damaged Kenya’s fast-growing economy, particularly its tourism industry, one of its main sources of foreign-exchange revenue.

After marching toward Kismayo for nearly a year, Kenyan forces in recent weeks began bombarding the town from the ocean and by air, prompting thousands of residents to flee, according to aid agencies.

As its control of population centers has shrunk, the al-Shabab militia has intensified guerrilla attacks in Mogadishu in the past several weeks, dispatching suicide bombers and assassinating government officials and journalists.

Observers say they expect something similar to unfold in Kismayo, with the militia striking from underground if it no longer controls the port and the town itself.