set off by

[1235]

Observers noted that Carney’s praise of Pakistan came amid tensions in Washington-Islamabad ties set off by the unilateral American raid of Abbottabad in May during which Osama bin Laden was killed.
Please tell me underlined word.

[BobK]

ignited, sparked off

I think 'ties' may be either a typo (not sure of what though) or a bad translation of a word like relations.

b

[shroob]

Observers noted that Carney’s praise of Pakistan came amid tensions in Washington-Islamabad ties set off by the unilateral American raid of Abbottabad in May during which Osama bin Laden was killed.
Please tell me underlined words.

In this context, 'set off by' could be replaced by 'caused', 'made worse by', or 'aggrivated by'.

In other words, Carney's praise for Pakistan came at a time when the Washington-Islamabad relationship was stressed, due to an American raid which killed Osama bin Laden, which was done without telling the Pakistani government.