It is sabotage. It means to damage or destroy as an act of subversion against an organization or nation.

VOA: special.2010.04.18

He said the attempt by the United States to strengthen its force at Fort Sumter was clearly an act of aggression.

VOA: special.2009.07.23

But any attempt to send more men or supplies would be seen as an act of war civil war.

VOA: special.2009.07.30

ALLEN: " Well,at two o'clock, our billing changes." SECRETARY: "Well, what kind of an act do you do?"

VOA: special.2009.03.09

They did not wait for Norway or Belgium or the Netherlands to commit an act of war."

VOA: special.2010.01.31

Therefore,to send troops to a state where federal officers had resigned such as South Carolina would be an act of war against the state.

VOA: special.2009.07.16

If,the commander said, the governor had approved the shelling, it would be an act of war.

VOA: special.2009.07.23

The National Arboretum was established by an act of Congress in nineteen twenty-seven.

VOA: special.2010.10.01

The movement of American troops there, they said,was an act of war.

VOA: special.2009.02.26

Some said his raid was an act of war.

VOA: special.2009.07.02

It is a scenario that has become all but routine - an act of piracy on the high seas by Somalis.

VOA: standard.2010.04.20

An act of Congress requires a cut-off of most U.S.aid to countries where elected governments are unseated by the military.

VOA: standard.2009.07.01

North Korea says attempts to shoot down its rocket will be an act of war, and that any additional U.N.

VOA: standard.2009.03.27

Israel says its three-week assault on the Gaza Strip was an act of legitimate self-defense in response to years of Palestinian rocket attacks.

VOA: standard.2009.10.16