The letter threatened to use biochemical weapons if the blind sheik was not released.
1	The	the	DET	DT	Definite=Def|PronType=Art	2	det	2:det	_
2	letter	letter	NOUN	NN	Number=Sing	3	nsubj	3:nsubj|5:nsubj:xsubj	_
3	threatened	threaten	VERB	VBD	Mood=Ind|Number=Sing|Person=3|Tense=Past|VerbForm=Fin	0	root	0:root	_
4	to	to	PART	TO	_	5	mark	5:mark	_
5	use	use	VERB	VB	VerbForm=Inf	3	xcomp	3:xcomp	_
6	biochemical	biochemical	ADJ	JJ	Degree=Pos	7	amod	7:amod	_
7	weapons	weapon	NOUN	NNS	Number=Plur	5	obj	5:obj	_
8	if	if	SCONJ	IN	_	14	mark	14:mark	_
9	the	the	DET	DT	Definite=Def|PronType=Art	11	det	11:det	_
10	blind	blind	ADJ	JJ	Degree=Pos	11	amod	11:amod	_
11	sheik	sheik	NOUN	NN	Number=Sing	14	nsubj:pass	14:nsubj:pass	_
12	was	be	AUX	VBD	Mood=Ind|Number=Sing|Person=3|Tense=Past|VerbForm=Fin	14	aux:pass	14:aux:pass	_
13	not	not	PART	RB	_	14	advmod	14:advmod	_
14	released	release	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	5	advcl	5:advcl:if	SpaceAfter=No
15	.	.	PUNCT	.	_	3	punct	3:punct	_
