On April 9, 2003, Baghdad was formally secured. As the summer of 2003 gave way to autumn, the pattern of anti-occupation attacks shifted to include repeated, deadly suicide car bombings against high-profile targets in Baghdad, such as the headquarters of the UN and the Red Cross, foreign embassies, and police stations of the newly-formed post-Saddam Iraqi police force. At the same time, attacks on individual U.S. soldiers and vehicles, often in the form of buried roadside bombs, went on. The coalition counterinsurgency began on June 9, 2003 in response to an increase in guerilla attacks that began in late May.
The invasion itself was swift, with the collapse of the Iraq government and the military of Iraq in about three weeks. Coalition forces moved into Baghdad with limited resistance; Iraqi government officials had either disappeared or had conceded defeat.
For an extensive list of weaponry used by the Iraqi Army at the beginning of the war, see Military of Iraq.
Currently, armed Iraqi resistance is composed of over a dozen major insurgent organizations and countless smaller cells. Foreign fighters and Islamists have entered the country, mostly through the porous desert borders of Syria and Saudi Arabia. Iraqi guerillas operate in small squad sized formations of five to ten men. Assaults combining the following weapons and tactics, involving IEDs, RPGs, mortars, and car bombs all at once, have increasingly appeared.