Somalia's branch of the al-Qaida network has threatened Westerners and the neighboring state of Kenya, over successful advances against the militant group. According to several reports, French warships and American forces have joined the bombardment of al-Shabaab.

Kenyan authorities increased security in Nairobi following a grenade attack on a bar early Monday morning. "There is every reason to believe they are responsible and yes we are linking this attack to the Al Shabaab threats," said Nairobi police chief Antony Kibuchi. Authorities also said that the attacker used the same type of Russian grenade as a previous attack on Nairobi bus last year, making the most recent attack the first since Kenyan troops invaded Somali territory this year.

The U.S. Embassy in Kenya had issued a warning on Saturday to American citizens about potential attacks "at prominent Kenyan facilities and areas where foreigners are known to congregate, such as malls and night clubs." The statement added that measures had been taken to limit visits by American government officials and it warned citizens to defer their travel to Kenya. Secretary of State Hillary Clinton had also warned of a "various serious threat" to Westerners in Kenya, during an interview Sunday on ABC.

Al-Shabaab's retaliatory attack came after a Kenyan advance into its southern Somali territory. France denied a Kenyan claim that French navy bombarded a Shabaab stronghold, but admitted it was providing aid to Kenya's offensive. Kenya has also claimed that the United States had stepped up the aerial bombardment of Shabaab positions over the past few days, although the U.S. ambassador to Kenya said the support was only technical.