Kabul, Afghanistan (CNN) Five militants targeted a military base in Kabul on Monday, killing 11 and capping a week of violence that has shaken a country ravaged by years of conflict.

More than 130 people have been killed in four attacks over the past nine days, starting with a deadly hotel siege in Kabul which left at least 22 people dead.

The Taliban have claimed two attacks while ISIS says it is behind the others, including Monday's military base assault, raising the possibility of a deadly competition between the two terrorist groups.

Meanwhile, the fact a military base in the center of Kabul was vulnerable to attack raises questions over the Afghan government's ability to protect itself.

"This is all about the deterioration of security inside what was supposed to be known as the 'ring of steel,' the Afghan capital of Kabul ... (ISIS) appears to be in a race for the low ground of extremist brutality with the Taliban," CNN's Nick Paton Walsh said.