Israel has been using the D9 bulldozer for combat operations since the 1960s. But there has always been a problem with getting repairs made close to the fighting itself. There were never enough D9s in service to justify training soldiers to do complex repairs. Instead, civilian technicians, sometimes employees of the manufacturer (Caterpillar) were brought in. Israel recently solved the problem, by making those D9 tech who are Israeli civilians, members of the army reserve. This solved a lot of legal and administrative matters (like who pays if the technicians are hurt while making battlefield repairs), and got the techs some extra money for the additional risk of getting shot at while patching up the D9s.
The 62 ton D-9 armored (via an Israeli armor kit) bulldozer has been an important tool for urban warfare. The Israelis, like the Americans, pioneered the use of special explosives to blast entry holes through walls, so troops can quickly get to their objectives. But the D-9 lets you bash through buildings, or even shake the enemy out of some buildings. Thus the D9 proved very effective in urban combat. The Israelis often mount a machine-gun on the D9s, to provide additional protection. The D9s often survive large (several hundred pound) roadside bombs and RPG hits.
In early 2003, the U.S. bought nine 62 ton D9 armored Caterpillar bulldozers into Kuwait for the Iraq campaign. The D9s, and their Israeli made armor kit, were purchased because of the Israeli success with the dozer in urban warfare against Palestinian terrorists. America had used the D9 during the 1960s in Vietnam, but after that only used the smaller (35 ton, with armor kit) D7. The D9 was not needed for urban fighting in Iraq during 2003, but was found very useful (much more so than the smaller D7) for combat engineering tasks. The D9 quickly cleared highways of debris and built temporary roads for combat vehicles. D9s was eventually used in Iraq for combat operations in places like Fallujah.